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vector-pinnable-header-pin-button" data-event-name="pinnable-header.vector-toc.pin">sposta nella barra laterale</button> <button class="vector-pinnable-header-toggle-button vector-pinnable-header-unpin-button" data-event-name="pinnable-header.vector-toc.unpin">nascondi</button> </div> <ul class="vector-toc-contents" id="mw-panel-toc-list"> <li id="toc-mw-content-text" class="vector-toc-list-item vector-toc-level-1"> <a href="#" class="vector-toc-link"> <div class="vector-toc-text">Inizio</div> </a> </li> <li id="toc-Descrizione" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#Descrizione"> <div class="vector-toc-text"> <span class="vector-toc-numb">1</span> <span>Descrizione</span> </div> </a> <button aria-controls="toc-Descrizione-sublist" class="cdx-button cdx-button--weight-quiet cdx-button--icon-only vector-toc-toggle"> <span class="vector-icon mw-ui-icon-wikimedia-expand"></span> <span>Attiva/disattiva la sottosezione Descrizione</span> </button> <ul id="toc-Descrizione-sublist" class="vector-toc-list"> <li id="toc-Conduzione_elettrica" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Conduzione_elettrica"> <div class="vector-toc-text"> <span class="vector-toc-numb">1.1</span> <span>Conduzione elettrica</span> </div> </a> <ul id="toc-Conduzione_elettrica-sublist" class="vector-toc-list"> </ul> </li> </ul> </li> <li id="toc-Grandezze_fisiche" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#Grandezze_fisiche"> <div class="vector-toc-text"> <span class="vector-toc-numb">2</span> <span>Grandezze fisiche</span> </div> </a> <button aria-controls="toc-Grandezze_fisiche-sublist" class="cdx-button cdx-button--weight-quiet cdx-button--icon-only vector-toc-toggle"> <span class="vector-icon mw-ui-icon-wikimedia-expand"></span> <span>Attiva/disattiva la sottosezione Grandezze fisiche</span> </button> <ul id="toc-Grandezze_fisiche-sublist" class="vector-toc-list"> <li id="toc-Velocità_di_deriva" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Velocità_di_deriva"> <div class="vector-toc-text"> <span class="vector-toc-numb">2.1</span> <span>Velocità di deriva</span> </div> </a> <ul id="toc-Velocità_di_deriva-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Intensità_di_corrente" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Intensità_di_corrente"> <div class="vector-toc-text"> <span class="vector-toc-numb">2.2</span> <span>Intensità di corrente</span> </div> </a> <ul id="toc-Intensità_di_corrente-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Densità_di_corrente_elettrica" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Densità_di_corrente_elettrica"> <div class="vector-toc-text"> <span class="vector-toc-numb">2.3</span> <span>Densità di corrente elettrica</span> </div> </a> <ul id="toc-Densità_di_corrente_elettrica-sublist" class="vector-toc-list"> <li id="toc-Legge_di_conservazione_della_carica_elettrica" class="vector-toc-list-item vector-toc-level-3"> <a class="vector-toc-link" href="#Legge_di_conservazione_della_carica_elettrica"> <div class="vector-toc-text"> <span class="vector-toc-numb">2.3.1</span> <span>Legge di conservazione della carica elettrica</span> </div> </a> <ul id="toc-Legge_di_conservazione_della_carica_elettrica-sublist" class="vector-toc-list"> </ul> </li> </ul> </li> </ul> </li> <li id="toc-Quadricorrente_elettrica" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#Quadricorrente_elettrica"> <div class="vector-toc-text"> <span class="vector-toc-numb">3</span> <span>Quadricorrente elettrica</span> </div> </a> <ul id="toc-Quadricorrente_elettrica-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Pericolosità_della_corrente" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#Pericolosità_della_corrente"> <div class="vector-toc-text"> <span class="vector-toc-numb">4</span> <span>Pericolosità della corrente</span> </div> </a> <ul id="toc-Pericolosità_della_corrente-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Note" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#Note"> <div class="vector-toc-text"> <span class="vector-toc-numb">5</span> <span>Note</span> </div> </a> <ul id="toc-Note-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Bibliografia" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#Bibliografia"> <div class="vector-toc-text"> <span class="vector-toc-numb">6</span> <span>Bibliografia</span> </div> </a> <ul id="toc-Bibliografia-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Voci_correlate" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#Voci_correlate"> <div class="vector-toc-text"> <span class="vector-toc-numb">7</span> <span>Voci correlate</span> </div> </a> <ul id="toc-Voci_correlate-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Altri_progetti" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#Altri_progetti"> <div class="vector-toc-text"> <span class="vector-toc-numb">8</span> <span>Altri progetti</span> </div> </a> <ul id="toc-Altri_progetti-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Collegamenti_esterni" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#Collegamenti_esterni"> <div class="vector-toc-text"> <span class="vector-toc-numb">9</span> <span>Collegamenti esterni</span> </div> </a> <ul id="toc-Collegamenti_esterni-sublist" class="vector-toc-list"> </ul> </li> </ul> </div> </div> </nav> </div> </div> <div class="mw-content-container"> <main id="content" class="mw-body"> <header class="mw-body-header vector-page-titlebar"> <nav aria-label="Indice" class="vector-toc-landmark"> <div id="vector-page-titlebar-toc" class="vector-dropdown vector-page-titlebar-toc vector-button-flush-left" > <input type="checkbox" id="vector-page-titlebar-toc-checkbox" role="button" aria-haspopup="true" data-event-name="ui.dropdown-vector-page-titlebar-toc" class="vector-dropdown-checkbox " aria-label="Mostra/Nascondi l'indice" > <label id="vector-page-titlebar-toc-label" for="vector-page-titlebar-toc-checkbox" class="vector-dropdown-label cdx-button cdx-button--fake-button cdx-button--fake-button--enabled cdx-button--weight-quiet cdx-button--icon-only " aria-hidden="true" ><span class="vector-icon mw-ui-icon-listBullet mw-ui-icon-wikimedia-listBullet"></span> <span class="vector-dropdown-label-text">Mostra/Nascondi l'indice</span> </label> <div class="vector-dropdown-content"> <div id="vector-page-titlebar-toc-unpinned-container" class="vector-unpinned-container"> </div> </div> </div> </nav> <h1 id="firstHeading" class="firstHeading mw-first-heading"><span class="mw-page-title-main">Corrente elettrica</span></h1> <div id="p-lang-btn" class="vector-dropdown mw-portlet mw-portlet-lang" > <input type="checkbox" id="p-lang-btn-checkbox" role="button" aria-haspopup="true" data-event-name="ui.dropdown-p-lang-btn" class="vector-dropdown-checkbox mw-interlanguage-selector" aria-label="Vai a una voce in un'altra lingua. Disponibile in 127 lingue" > <label id="p-lang-btn-label" for="p-lang-btn-checkbox" class="vector-dropdown-label cdx-button cdx-button--fake-button cdx-button--fake-button--enabled cdx-button--weight-quiet cdx-button--action-progressive mw-portlet-lang-heading-127" aria-hidden="true" ><span class="vector-icon mw-ui-icon-language-progressive mw-ui-icon-wikimedia-language-progressive"></span> <span class="vector-dropdown-label-text">127 lingue</span> </label> <div class="vector-dropdown-content"> <div class="vector-menu-content"> <ul class="vector-menu-content-list"> <li class="interlanguage-link interwiki-af mw-list-item"><a href="https://af.wikipedia.org/wiki/Elektriese_stroom" title="Elektriese stroom - afrikaans" lang="af" hreflang="af" data-title="Elektriese stroom" data-language-autonym="Afrikaans" data-language-local-name="afrikaans" class="interlanguage-link-target"><span>Afrikaans</span></a></li><li class="interlanguage-link interwiki-als mw-list-item"><a href="https://als.wikipedia.org/wiki/Elektrischer_Strom" title="Elektrischer Strom - tedesco svizzero" lang="gsw" hreflang="gsw" data-title="Elektrischer Strom" data-language-autonym="Alemannisch" data-language-local-name="tedesco svizzero" class="interlanguage-link-target"><span>Alemannisch</span></a></li><li class="interlanguage-link interwiki-an mw-list-item"><a href="https://an.wikipedia.org/wiki/Corrient_electrica" title="Corrient electrica - aragonese" lang="an" hreflang="an" data-title="Corrient electrica" data-language-autonym="Aragonés" data-language-local-name="aragonese" class="interlanguage-link-target"><span>Aragonés</span></a></li><li class="interlanguage-link interwiki-ar mw-list-item"><a href="https://ar.wikipedia.org/wiki/%D8%AA%D9%8A%D8%A7%D8%B1_%D9%83%D9%87%D8%B1%D8%A8%D8%A7%D8%A6%D9%8A" title="تيار كهربائي - arabo" lang="ar" hreflang="ar" data-title="تيار كهربائي" data-language-autonym="العربية" data-language-local-name="arabo" class="interlanguage-link-target"><span>العربية</span></a></li><li class="interlanguage-link interwiki-ary mw-list-item"><a href="https://ary.wikipedia.org/wiki/%D8%B3%D8%A7%D8%B1%D8%AD_%D8%AF_%D8%A7%D9%84%D8%AA%D8%B1%D9%8A%D8%B3%D9%8A%D9%86%D8%AA%D9%8A" title="سارح د التريسينتي - arabo marocchino" lang="ary" hreflang="ary" data-title="سارح د التريسينتي" data-language-autonym="الدارجة" data-language-local-name="arabo marocchino" class="interlanguage-link-target"><span>الدارجة</span></a></li><li class="interlanguage-link interwiki-ast mw-list-item"><a href="https://ast.wikipedia.org/wiki/Corriente_ll%C3%A9trico" title="Corriente llétrico - asturiano" lang="ast" hreflang="ast" data-title="Corriente llétrico" data-language-autonym="Asturianu" data-language-local-name="asturiano" class="interlanguage-link-target"><span>Asturianu</span></a></li><li class="interlanguage-link interwiki-az mw-list-item"><a href="https://az.wikipedia.org/wiki/Elektrik_c%C9%99r%C9%99yan%C4%B1" title="Elektrik cərəyanı - azerbaigiano" lang="az" hreflang="az" data-title="Elektrik cərəyanı" data-language-autonym="Azərbaycanca" data-language-local-name="azerbaigiano" class="interlanguage-link-target"><span>Azərbaycanca</span></a></li><li class="interlanguage-link interwiki-azb mw-list-item"><a href="https://azb.wikipedia.org/wiki/%D8%A7%D9%84%DA%A9%D8%AA%D8%B1%DB%8C%DA%A9_%D8%A2%D8%AE%DB%8C%D9%85%DB%8C" title="الکتریک آخیمی - South Azerbaijani" lang="azb" hreflang="azb" data-title="الکتریک آخیمی" data-language-autonym="تۆرکجه" data-language-local-name="South Azerbaijani" class="interlanguage-link-target"><span>تۆرکجه</span></a></li><li class="interlanguage-link interwiki-ba mw-list-item"><a href="https://ba.wikipedia.org/wiki/%D0%AD%D0%BB%D0%B5%D0%BA%D1%82%D1%80_%D1%82%D0%BE%D0%B3%D1%8B" title="Электр тогы - baschiro" lang="ba" hreflang="ba" data-title="Электр тогы" data-language-autonym="Башҡортса" data-language-local-name="baschiro" class="interlanguage-link-target"><span>Башҡортса</span></a></li><li class="interlanguage-link interwiki-bar mw-list-item"><a href="https://bar.wikipedia.org/wiki/Elektrischa_Strom" title="Elektrischa Strom - bavarese" lang="bar" hreflang="bar" data-title="Elektrischa Strom" data-language-autonym="Boarisch" data-language-local-name="bavarese" class="interlanguage-link-target"><span>Boarisch</span></a></li><li class="interlanguage-link interwiki-bat-smg mw-list-item"><a href="https://bat-smg.wikipedia.org/wiki/Alektr%C4%97n%C4%97_srauj%C4%97" title="Alektrėnė sraujė - samogitico" lang="sgs" hreflang="sgs" data-title="Alektrėnė sraujė" data-language-autonym="Žemaitėška" data-language-local-name="samogitico" class="interlanguage-link-target"><span>Žemaitėška</span></a></li><li class="interlanguage-link interwiki-bcl mw-list-item"><a href="https://bcl.wikipedia.org/wiki/Elektrikong_kuryente" title="Elektrikong kuryente - Central Bikol" lang="bcl" hreflang="bcl" data-title="Elektrikong kuryente" data-language-autonym="Bikol Central" data-language-local-name="Central Bikol" class="interlanguage-link-target"><span>Bikol Central</span></a></li><li class="interlanguage-link interwiki-be mw-list-item"><a href="https://be.wikipedia.org/wiki/%D0%AD%D0%BB%D0%B5%D0%BA%D1%82%D1%80%D1%8B%D1%87%D0%BD%D1%8B_%D1%82%D0%BE%D0%BA" title="Электрычны ток - bielorusso" lang="be" hreflang="be" data-title="Электрычны ток" data-language-autonym="Беларуская" data-language-local-name="bielorusso" class="interlanguage-link-target"><span>Беларуская</span></a></li><li class="interlanguage-link interwiki-be-x-old mw-list-item"><a href="https://be-tarask.wikipedia.org/wiki/%D0%AD%D0%BB%D0%B5%D0%BA%D1%82%D1%80%D1%8B%D1%87%D0%BD%D1%8B_%D1%82%D0%BE%D0%BA" title="Электрычны ток - Belarusian (Taraškievica orthography)" lang="be-tarask" hreflang="be-tarask" data-title="Электрычны ток" data-language-autonym="Беларуская (тарашкевіца)" data-language-local-name="Belarusian (Taraškievica orthography)" class="interlanguage-link-target"><span>Беларуская (тарашкевіца)</span></a></li><li class="interlanguage-link interwiki-bg mw-list-item"><a href="https://bg.wikipedia.org/wiki/%D0%95%D0%BB%D0%B5%D0%BA%D1%82%D1%80%D0%B8%D1%87%D0%B5%D1%81%D0%BA%D0%B8_%D1%82%D0%BE%D0%BA" title="Електрически ток - bulgaro" lang="bg" hreflang="bg" data-title="Електрически ток" data-language-autonym="Български" data-language-local-name="bulgaro" class="interlanguage-link-target"><span>Български</span></a></li><li class="interlanguage-link interwiki-bn mw-list-item"><a href="https://bn.wikipedia.org/wiki/%E0%A6%A4%E0%A6%A1%E0%A6%BC%E0%A6%BF%E0%A7%8E_%E0%A6%AA%E0%A7%8D%E0%A6%B0%E0%A6%AC%E0%A6%BE%E0%A6%B9" title="তড়িৎ প্রবাহ - bengalese" lang="bn" hreflang="bn" data-title="তড়িৎ প্রবাহ" data-language-autonym="বাংলা" data-language-local-name="bengalese" class="interlanguage-link-target"><span>বাংলা</span></a></li><li class="interlanguage-link interwiki-bs mw-list-item"><a href="https://bs.wikipedia.org/wiki/Elektri%C4%8Dna_struja" title="Električna struja - bosniaco" lang="bs" hreflang="bs" data-title="Električna struja" data-language-autonym="Bosanski" data-language-local-name="bosniaco" class="interlanguage-link-target"><span>Bosanski</span></a></li><li class="interlanguage-link interwiki-bxr mw-list-item"><a href="https://bxr.wikipedia.org/wiki/%D0%A1%D0%B0%D1%85%D0%B8%D0%BB%D0%B3%D0%B0%D0%B0%D0%BD_%D0%B3%D2%AF%D0%B9%D0%B4%D1%8D%D0%BB" title="Сахилгаан гүйдэл - Russia Buriat" lang="bxr" hreflang="bxr" data-title="Сахилгаан гүйдэл" data-language-autonym="Буряад" data-language-local-name="Russia Buriat" class="interlanguage-link-target"><span>Буряад</span></a></li><li class="interlanguage-link interwiki-ca mw-list-item"><a href="https://ca.wikipedia.org/wiki/Corrent_el%C3%A8ctric" title="Corrent elèctric - catalano" lang="ca" hreflang="ca" data-title="Corrent elèctric" data-language-autonym="Català" data-language-local-name="catalano" class="interlanguage-link-target"><span>Català</span></a></li><li class="interlanguage-link interwiki-ce mw-list-item"><a href="https://ce.wikipedia.org/wiki/%D0%A2%D0%BE%D0%BA" title="Ток - ceceno" lang="ce" hreflang="ce" data-title="Ток" data-language-autonym="Нохчийн" data-language-local-name="ceceno" class="interlanguage-link-target"><span>Нохчийн</span></a></li><li class="interlanguage-link interwiki-ckb mw-list-item"><a href="https://ckb.wikipedia.org/wiki/%D8%AA%DB%95%D8%B2%D9%88%D9%88%DB%8C_%DA%A9%D8%A7%D8%B1%DB%95%D8%A8%D8%A7%DB%8C%DB%8C" title="تەزووی کارەبایی - curdo centrale" lang="ckb" hreflang="ckb" data-title="تەزووی کارەبایی" data-language-autonym="کوردی" data-language-local-name="curdo centrale" class="interlanguage-link-target"><span>کوردی</span></a></li><li class="interlanguage-link interwiki-cs mw-list-item"><a href="https://cs.wikipedia.org/wiki/Elektrick%C3%BD_proud" title="Elektrický proud - ceco" lang="cs" hreflang="cs" data-title="Elektrický proud" data-language-autonym="Čeština" data-language-local-name="ceco" class="interlanguage-link-target"><span>Čeština</span></a></li><li class="interlanguage-link interwiki-cv mw-list-item"><a href="https://cv.wikipedia.org/wiki/%D0%AD%D0%BB%D0%B5%D0%BA%D1%82%D1%80%D0%BE_%D1%82%D0%BE%D0%BA" title="Электро ток - ciuvascio" lang="cv" hreflang="cv" data-title="Электро ток" data-language-autonym="Чӑвашла" data-language-local-name="ciuvascio" class="interlanguage-link-target"><span>Чӑвашла</span></a></li><li class="interlanguage-link interwiki-cy mw-list-item"><a href="https://cy.wikipedia.org/wiki/Cerrynt_trydanol" title="Cerrynt trydanol - gallese" lang="cy" hreflang="cy" data-title="Cerrynt trydanol" data-language-autonym="Cymraeg" data-language-local-name="gallese" class="interlanguage-link-target"><span>Cymraeg</span></a></li><li class="interlanguage-link interwiki-da mw-list-item"><a href="https://da.wikipedia.org/wiki/Elektrisk_str%C3%B8m" title="Elektrisk strøm - danese" lang="da" hreflang="da" data-title="Elektrisk strøm" data-language-autonym="Dansk" data-language-local-name="danese" class="interlanguage-link-target"><span>Dansk</span></a></li><li class="interlanguage-link interwiki-de mw-list-item"><a href="https://de.wikipedia.org/wiki/Elektrischer_Strom" title="Elektrischer Strom - tedesco" lang="de" hreflang="de" data-title="Elektrischer Strom" data-language-autonym="Deutsch" data-language-local-name="tedesco" class="interlanguage-link-target"><span>Deutsch</span></a></li><li class="interlanguage-link interwiki-el mw-list-item"><a href="https://el.wikipedia.org/wiki/%CE%97%CE%BB%CE%B5%CE%BA%CF%84%CF%81%CE%B9%CE%BA%CF%8C_%CF%81%CE%B5%CF%8D%CE%BC%CE%B1" title="Ηλεκτρικό ρεύμα - greco" lang="el" hreflang="el" data-title="Ηλεκτρικό ρεύμα" data-language-autonym="Ελληνικά" data-language-local-name="greco" class="interlanguage-link-target"><span>Ελληνικά</span></a></li><li class="interlanguage-link interwiki-en mw-list-item"><a href="https://en.wikipedia.org/wiki/Electric_current" title="Electric current - inglese" lang="en" hreflang="en" data-title="Electric current" data-language-autonym="English" data-language-local-name="inglese" class="interlanguage-link-target"><span>English</span></a></li><li class="interlanguage-link interwiki-eo mw-list-item"><a href="https://eo.wikipedia.org/wiki/Elektra_kurento" title="Elektra kurento - esperanto" lang="eo" hreflang="eo" data-title="Elektra kurento" data-language-autonym="Esperanto" data-language-local-name="esperanto" class="interlanguage-link-target"><span>Esperanto</span></a></li><li class="interlanguage-link interwiki-es mw-list-item"><a href="https://es.wikipedia.org/wiki/Corriente_el%C3%A9ctrica" title="Corriente eléctrica - spagnolo" lang="es" hreflang="es" data-title="Corriente eléctrica" data-language-autonym="Español" data-language-local-name="spagnolo" class="interlanguage-link-target"><span>Español</span></a></li><li class="interlanguage-link interwiki-et mw-list-item"><a href="https://et.wikipedia.org/wiki/Elektrivool" title="Elektrivool - estone" lang="et" hreflang="et" data-title="Elektrivool" data-language-autonym="Eesti" data-language-local-name="estone" class="interlanguage-link-target"><span>Eesti</span></a></li><li class="interlanguage-link interwiki-eu mw-list-item"><a href="https://eu.wikipedia.org/wiki/Korronte_elektriko" title="Korronte elektriko - basco" lang="eu" hreflang="eu" data-title="Korronte elektriko" data-language-autonym="Euskara" data-language-local-name="basco" class="interlanguage-link-target"><span>Euskara</span></a></li><li class="interlanguage-link interwiki-fa mw-list-item"><a href="https://fa.wikipedia.org/wiki/%D8%AC%D8%B1%DB%8C%D8%A7%D9%86_%D8%A7%D9%84%DA%A9%D8%AA%D8%B1%DB%8C%DA%A9%DB%8C" title="جریان الکتریکی - persiano" lang="fa" hreflang="fa" data-title="جریان الکتریکی" data-language-autonym="فارسی" data-language-local-name="persiano" class="interlanguage-link-target"><span>فارسی</span></a></li><li class="interlanguage-link interwiki-fi mw-list-item"><a href="https://fi.wikipedia.org/wiki/S%C3%A4hk%C3%B6virta" title="Sähkövirta - finlandese" lang="fi" hreflang="fi" data-title="Sähkövirta" data-language-autonym="Suomi" data-language-local-name="finlandese" class="interlanguage-link-target"><span>Suomi</span></a></li><li class="interlanguage-link interwiki-fr mw-list-item"><a href="https://fr.wikipedia.org/wiki/Courant_%C3%A9lectrique" title="Courant électrique - francese" lang="fr" hreflang="fr" data-title="Courant électrique" data-language-autonym="Français" data-language-local-name="francese" class="interlanguage-link-target"><span>Français</span></a></li><li class="interlanguage-link interwiki-frr mw-list-item"><a href="https://frr.wikipedia.org/wiki/Stroom" title="Stroom - frisone settentrionale" lang="frr" hreflang="frr" data-title="Stroom" data-language-autonym="Nordfriisk" data-language-local-name="frisone settentrionale" class="interlanguage-link-target"><span>Nordfriisk</span></a></li><li class="interlanguage-link interwiki-ga mw-list-item"><a href="https://ga.wikipedia.org/wiki/Sruth_leictreach" title="Sruth leictreach - irlandese" lang="ga" hreflang="ga" data-title="Sruth leictreach" data-language-autonym="Gaeilge" data-language-local-name="irlandese" class="interlanguage-link-target"><span>Gaeilge</span></a></li><li class="interlanguage-link interwiki-gl mw-list-item"><a href="https://gl.wikipedia.org/wiki/Corrente_el%C3%A9ctrica" title="Corrente eléctrica - galiziano" lang="gl" hreflang="gl" data-title="Corrente eléctrica" data-language-autonym="Galego" data-language-local-name="galiziano" class="interlanguage-link-target"><span>Galego</span></a></li><li class="interlanguage-link interwiki-gor mw-list-item"><a href="https://gor.wikipedia.org/wiki/Arus_listrik" title="Arus listrik - gorontalo" lang="gor" hreflang="gor" data-title="Arus listrik" data-language-autonym="Bahasa Hulontalo" data-language-local-name="gorontalo" class="interlanguage-link-target"><span>Bahasa Hulontalo</span></a></li><li class="interlanguage-link interwiki-he mw-list-item"><a href="https://he.wikipedia.org/wiki/%D7%96%D7%A8%D7%9D_%D7%97%D7%A9%D7%9E%D7%9C%D7%99" title="זרם חשמלי - ebraico" lang="he" hreflang="he" data-title="זרם חשמלי" data-language-autonym="עברית" data-language-local-name="ebraico" class="interlanguage-link-target"><span>עברית</span></a></li><li class="interlanguage-link interwiki-hi mw-list-item"><a href="https://hi.wikipedia.org/wiki/%E0%A4%B5%E0%A4%BF%E0%A4%A6%E0%A5%8D%E0%A4%AF%E0%A5%81%E0%A4%A4_%E0%A4%A7%E0%A4%BE%E0%A4%B0%E0%A4%BE" title="विद्युत धारा - hindi" lang="hi" hreflang="hi" data-title="विद्युत धारा" data-language-autonym="हिन्दी" data-language-local-name="hindi" class="interlanguage-link-target"><span>हिन्दी</span></a></li><li class="interlanguage-link interwiki-hif mw-list-item"><a href="https://hif.wikipedia.org/wiki/Electric_current" title="Electric current - hindi figiano" lang="hif" hreflang="hif" data-title="Electric current" data-language-autonym="Fiji Hindi" data-language-local-name="hindi figiano" class="interlanguage-link-target"><span>Fiji Hindi</span></a></li><li class="interlanguage-link interwiki-hr mw-list-item"><a href="https://hr.wikipedia.org/wiki/Elektri%C4%8Dna_struja" title="Električna struja - croato" lang="hr" hreflang="hr" data-title="Električna struja" data-language-autonym="Hrvatski" data-language-local-name="croato" class="interlanguage-link-target"><span>Hrvatski</span></a></li><li class="interlanguage-link interwiki-ht mw-list-item"><a href="https://ht.wikipedia.org/wiki/Kouran_elektrik" title="Kouran elektrik - creolo haitiano" lang="ht" hreflang="ht" data-title="Kouran elektrik" data-language-autonym="Kreyòl ayisyen" data-language-local-name="creolo haitiano" class="interlanguage-link-target"><span>Kreyòl ayisyen</span></a></li><li class="interlanguage-link interwiki-hu mw-list-item"><a href="https://hu.wikipedia.org/wiki/Elektromos_%C3%A1ram" title="Elektromos áram - ungherese" lang="hu" hreflang="hu" data-title="Elektromos áram" data-language-autonym="Magyar" data-language-local-name="ungherese" class="interlanguage-link-target"><span>Magyar</span></a></li><li class="interlanguage-link interwiki-hy mw-list-item"><a href="https://hy.wikipedia.org/wiki/%D4%B7%D5%AC%D5%A5%D5%AF%D5%BF%D6%80%D5%A1%D5%AF%D5%A1%D5%B6_%D5%B0%D5%B8%D5%BD%D5%A1%D5%B6%D6%84" title="Էլեկտրական հոսանք - armeno" lang="hy" hreflang="hy" data-title="Էլեկտրական հոսանք" data-language-autonym="Հայերեն" data-language-local-name="armeno" class="interlanguage-link-target"><span>Հայերեն</span></a></li><li class="interlanguage-link interwiki-ia mw-list-item"><a href="https://ia.wikipedia.org/wiki/Currente_electric" title="Currente electric - interlingua" lang="ia" hreflang="ia" data-title="Currente electric" data-language-autonym="Interlingua" data-language-local-name="interlingua" class="interlanguage-link-target"><span>Interlingua</span></a></li><li class="interlanguage-link interwiki-id mw-list-item"><a href="https://id.wikipedia.org/wiki/Arus_listrik" title="Arus listrik - indonesiano" lang="id" hreflang="id" data-title="Arus listrik" data-language-autonym="Bahasa Indonesia" data-language-local-name="indonesiano" class="interlanguage-link-target"><span>Bahasa Indonesia</span></a></li><li class="interlanguage-link interwiki-io mw-list-item"><a href="https://io.wikipedia.org/wiki/Korento" title="Korento - ido" lang="io" hreflang="io" data-title="Korento" data-language-autonym="Ido" data-language-local-name="ido" class="interlanguage-link-target"><span>Ido</span></a></li><li class="interlanguage-link interwiki-is mw-list-item"><a href="https://is.wikipedia.org/wiki/Rafstraumur" title="Rafstraumur - islandese" lang="is" hreflang="is" data-title="Rafstraumur" data-language-autonym="Íslenska" data-language-local-name="islandese" class="interlanguage-link-target"><span>Íslenska</span></a></li><li class="interlanguage-link interwiki-ja mw-list-item"><a href="https://ja.wikipedia.org/wiki/%E9%9B%BB%E6%B5%81" title="電流 - giapponese" lang="ja" hreflang="ja" data-title="電流" data-language-autonym="日本語" data-language-local-name="giapponese" class="interlanguage-link-target"><span>日本語</span></a></li><li class="interlanguage-link interwiki-ka mw-list-item"><a href="https://ka.wikipedia.org/wiki/%E1%83%94%E1%83%9A%E1%83%94%E1%83%A5%E1%83%A2%E1%83%A0%E1%83%A3%E1%83%9A%E1%83%98_%E1%83%93%E1%83%94%E1%83%9C%E1%83%98" title="ელექტრული დენი - georgiano" lang="ka" hreflang="ka" data-title="ელექტრული დენი" data-language-autonym="ქართული" data-language-local-name="georgiano" class="interlanguage-link-target"><span>ქართული</span></a></li><li class="interlanguage-link interwiki-kaa mw-list-item"><a href="https://kaa.wikipedia.org/wiki/Elektr_tog%C4%B1" title="Elektr togı - kara-kalpak" lang="kaa" hreflang="kaa" data-title="Elektr togı" data-language-autonym="Qaraqalpaqsha" data-language-local-name="kara-kalpak" class="interlanguage-link-target"><span>Qaraqalpaqsha</span></a></li><li class="interlanguage-link interwiki-kab mw-list-item"><a href="https://kab.wikipedia.org/wiki/A%E1%B8%8Dru_amestrisiti" title="Aḍru amestrisiti - cabilo" lang="kab" hreflang="kab" data-title="Aḍru amestrisiti" data-language-autonym="Taqbaylit" data-language-local-name="cabilo" class="interlanguage-link-target"><span>Taqbaylit</span></a></li><li class="interlanguage-link interwiki-kk mw-list-item"><a href="https://kk.wikipedia.org/wiki/%D0%AD%D0%BB%D0%B5%D0%BA%D1%82%D1%80_%D1%82%D0%BE%D0%B3%D1%8B" title="Электр тогы - kazako" lang="kk" hreflang="kk" data-title="Электр тогы" data-language-autonym="Қазақша" data-language-local-name="kazako" class="interlanguage-link-target"><span>Қазақша</span></a></li><li class="interlanguage-link interwiki-kn mw-list-item"><a href="https://kn.wikipedia.org/wiki/%E0%B2%B5%E0%B2%BF%E0%B2%A6%E0%B3%8D%E0%B2%AF%E0%B3%81%E0%B2%A4%E0%B3%8D_%E0%B2%AA%E0%B3%8D%E0%B2%B0%E0%B2%B5%E0%B2%BE%E0%B2%B9" title="ವಿದ್ಯುತ್ ಪ್ರವಾಹ - kannada" lang="kn" hreflang="kn" data-title="ವಿದ್ಯುತ್ ಪ್ರವಾಹ" data-language-autonym="ಕನ್ನಡ" data-language-local-name="kannada" class="interlanguage-link-target"><span>ಕನ್ನಡ</span></a></li><li class="interlanguage-link interwiki-ko mw-list-item"><a href="https://ko.wikipedia.org/wiki/%EC%A0%84%EB%A5%98" title="전류 - coreano" lang="ko" hreflang="ko" data-title="전류" data-language-autonym="한국어" data-language-local-name="coreano" class="interlanguage-link-target"><span>한국어</span></a></li><li class="interlanguage-link interwiki-ks mw-list-item"><a href="https://ks.wikipedia.org/wiki/%DA%AF%D8%B1%DB%8C%D9%9B%D9%86" title="گریٛن - kashmiri" lang="ks" hreflang="ks" data-title="گریٛن" data-language-autonym="कॉशुर / کٲشُر" data-language-local-name="kashmiri" class="interlanguage-link-target"><span>कॉशुर / کٲشُر</span></a></li><li class="interlanguage-link interwiki-ku mw-list-item"><a href="https://ku.wikipedia.org/wiki/Sir%C3%AAma_elektr%C3%AEk%C3%AA" title="Sirêma elektrîkê - curdo" lang="ku" hreflang="ku" data-title="Sirêma elektrîkê" data-language-autonym="Kurdî" data-language-local-name="curdo" class="interlanguage-link-target"><span>Kurdî</span></a></li><li class="interlanguage-link interwiki-kw mw-list-item"><a href="https://kw.wikipedia.org/wiki/Frosedh_tredanek" title="Frosedh tredanek - cornico" lang="kw" hreflang="kw" data-title="Frosedh tredanek" data-language-autonym="Kernowek" data-language-local-name="cornico" class="interlanguage-link-target"><span>Kernowek</span></a></li><li class="interlanguage-link interwiki-ky mw-list-item"><a href="https://ky.wikipedia.org/wiki/%D0%AD%D0%BB%D0%B5%D0%BA%D1%82%D1%80_%D1%82%D0%BE%D0%B3%D1%83" title="Электр тогу - kirghiso" lang="ky" hreflang="ky" data-title="Электр тогу" data-language-autonym="Кыргызча" data-language-local-name="kirghiso" class="interlanguage-link-target"><span>Кыргызча</span></a></li><li class="interlanguage-link interwiki-la mw-list-item"><a href="https://la.wikipedia.org/wiki/Fluxus_oneris_electrici" title="Fluxus oneris electrici - latino" lang="la" hreflang="la" data-title="Fluxus oneris electrici" data-language-autonym="Latina" data-language-local-name="latino" class="interlanguage-link-target"><span>Latina</span></a></li><li class="interlanguage-link interwiki-li mw-list-item"><a href="https://li.wikipedia.org/wiki/Elektrische_sjtroum" title="Elektrische sjtroum - limburghese" lang="li" hreflang="li" data-title="Elektrische sjtroum" data-language-autonym="Limburgs" data-language-local-name="limburghese" class="interlanguage-link-target"><span>Limburgs</span></a></li><li class="interlanguage-link interwiki-lmo mw-list-item"><a href="https://lmo.wikipedia.org/wiki/Corrent_elettrica" title="Corrent elettrica - lombardo" lang="lmo" hreflang="lmo" data-title="Corrent elettrica" data-language-autonym="Lombard" data-language-local-name="lombardo" class="interlanguage-link-target"><span>Lombard</span></a></li><li class="interlanguage-link interwiki-lt mw-list-item"><a href="https://lt.wikipedia.org/wiki/Elektros_srov%C4%97" title="Elektros srovė - lituano" lang="lt" hreflang="lt" data-title="Elektros srovė" data-language-autonym="Lietuvių" data-language-local-name="lituano" class="interlanguage-link-target"><span>Lietuvių</span></a></li><li class="interlanguage-link interwiki-lv mw-list-item"><a href="https://lv.wikipedia.org/wiki/Elektrisk%C4%81_str%C4%81va" title="Elektriskā strāva - lettone" lang="lv" hreflang="lv" data-title="Elektriskā strāva" data-language-autonym="Latviešu" data-language-local-name="lettone" class="interlanguage-link-target"><span>Latviešu</span></a></li><li class="interlanguage-link interwiki-mg mw-list-item"><a href="https://mg.wikipedia.org/wiki/Rianaratra" title="Rianaratra - malgascio" lang="mg" hreflang="mg" data-title="Rianaratra" data-language-autonym="Malagasy" data-language-local-name="malgascio" class="interlanguage-link-target"><span>Malagasy</span></a></li><li class="interlanguage-link interwiki-min mw-list-item"><a href="https://min.wikipedia.org/wiki/Arus_listrik" title="Arus listrik - menangkabau" lang="min" hreflang="min" data-title="Arus listrik" data-language-autonym="Minangkabau" data-language-local-name="menangkabau" class="interlanguage-link-target"><span>Minangkabau</span></a></li><li class="interlanguage-link interwiki-mk mw-list-item"><a href="https://mk.wikipedia.org/wiki/%D0%95%D0%BB%D0%B5%D0%BA%D1%82%D1%80%D0%B8%D1%87%D0%BD%D0%B0_%D1%81%D1%82%D1%80%D1%83%D1%98%D0%B0" title="Електрична струја - macedone" lang="mk" hreflang="mk" data-title="Електрична струја" data-language-autonym="Македонски" data-language-local-name="macedone" class="interlanguage-link-target"><span>Македонски</span></a></li><li class="interlanguage-link interwiki-ml mw-list-item"><a href="https://ml.wikipedia.org/wiki/%E0%B4%B5%E0%B5%88%E0%B4%A6%E0%B5%8D%E0%B4%AF%E0%B5%81%E0%B4%A4%E0%B4%A7%E0%B4%BE%E0%B4%B0" title="വൈദ്യുതധാര - malayalam" lang="ml" hreflang="ml" data-title="വൈദ്യുതധാര" data-language-autonym="മലയാളം" data-language-local-name="malayalam" class="interlanguage-link-target"><span>മലയാളം</span></a></li><li class="interlanguage-link interwiki-mn mw-list-item"><a href="https://mn.wikipedia.org/wiki/%D0%A6%D0%B0%D1%85%D0%B8%D0%BB%D0%B3%D0%B0%D0%B0%D0%BD_%D0%B3%D2%AF%D0%B9%D0%B4%D1%8D%D0%BB" title="Цахилгаан гүйдэл - mongolo" lang="mn" hreflang="mn" data-title="Цахилгаан гүйдэл" data-language-autonym="Монгол" data-language-local-name="mongolo" class="interlanguage-link-target"><span>Монгол</span></a></li><li class="interlanguage-link interwiki-mr mw-list-item"><a href="https://mr.wikipedia.org/wiki/%E0%A4%B5%E0%A4%BF%E0%A4%A6%E0%A5%8D%E0%A4%AF%E0%A5%81%E0%A4%A4_%E0%A4%A7%E0%A4%BE%E0%A4%B0%E0%A4%BE" title="विद्युत धारा - marathi" lang="mr" hreflang="mr" data-title="विद्युत धारा" data-language-autonym="मराठी" data-language-local-name="marathi" class="interlanguage-link-target"><span>मराठी</span></a></li><li class="interlanguage-link interwiki-ms mw-list-item"><a href="https://ms.wikipedia.org/wiki/Arus_elektrik" title="Arus elektrik - malese" lang="ms" hreflang="ms" data-title="Arus elektrik" data-language-autonym="Bahasa Melayu" data-language-local-name="malese" class="interlanguage-link-target"><span>Bahasa Melayu</span></a></li><li class="interlanguage-link interwiki-my mw-list-item"><a href="https://my.wikipedia.org/wiki/%E1%80%9C%E1%80%BB%E1%80%BE%E1%80%95%E1%80%BA%E1%80%85%E1%80%AE%E1%80%B8" title="လျှပ်စီး - birmano" lang="my" hreflang="my" data-title="လျှပ်စီး" data-language-autonym="မြန်မာဘာသာ" data-language-local-name="birmano" class="interlanguage-link-target"><span>မြန်မာဘာသာ</span></a></li><li class="interlanguage-link interwiki-ne mw-list-item"><a href="https://ne.wikipedia.org/wiki/%E0%A4%B5%E0%A4%BF%E0%A4%A6%E0%A5%8D%E0%A4%AF%E0%A5%81%E0%A4%A4_%E0%A4%A7%E0%A4%BE%E0%A4%B0%E0%A4%BE" title="विद्युत धारा - nepalese" lang="ne" hreflang="ne" data-title="विद्युत धारा" data-language-autonym="नेपाली" data-language-local-name="nepalese" class="interlanguage-link-target"><span>नेपाली</span></a></li><li class="interlanguage-link interwiki-nl mw-list-item"><a href="https://nl.wikipedia.org/wiki/Elektrische_stroom" title="Elektrische stroom - olandese" lang="nl" hreflang="nl" data-title="Elektrische stroom" data-language-autonym="Nederlands" data-language-local-name="olandese" class="interlanguage-link-target"><span>Nederlands</span></a></li><li class="interlanguage-link interwiki-nn mw-list-item"><a href="https://nn.wikipedia.org/wiki/Elektrisk_straum" title="Elektrisk straum - norvegese nynorsk" lang="nn" hreflang="nn" data-title="Elektrisk straum" data-language-autonym="Norsk nynorsk" data-language-local-name="norvegese nynorsk" class="interlanguage-link-target"><span>Norsk nynorsk</span></a></li><li class="interlanguage-link interwiki-no badge-Q17437796 badge-featuredarticle mw-list-item" title="voce in vetrina"><a href="https://no.wikipedia.org/wiki/Elektrisk_str%C3%B8m" title="Elektrisk strøm - norvegese bokmål" lang="nb" hreflang="nb" data-title="Elektrisk strøm" data-language-autonym="Norsk bokmål" data-language-local-name="norvegese bokmål" class="interlanguage-link-target"><span>Norsk bokmål</span></a></li><li class="interlanguage-link interwiki-oc mw-list-item"><a href="https://oc.wikipedia.org/wiki/Corrent_electric" title="Corrent electric - occitano" lang="oc" hreflang="oc" data-title="Corrent electric" data-language-autonym="Occitan" data-language-local-name="occitano" class="interlanguage-link-target"><span>Occitan</span></a></li><li class="interlanguage-link interwiki-om mw-list-item"><a href="https://om.wikipedia.org/wiki/Kaarentii_elektirikii" title="Kaarentii elektirikii - oromo" lang="om" hreflang="om" data-title="Kaarentii elektirikii" data-language-autonym="Oromoo" data-language-local-name="oromo" class="interlanguage-link-target"><span>Oromoo</span></a></li><li class="interlanguage-link interwiki-or mw-list-item"><a href="https://or.wikipedia.org/wiki/%E0%AC%AC%E0%AC%BF%E0%AC%A6%E0%AD%8D%E0%AD%9F%E0%AD%81%E0%AC%A4%E0%AD%8D_%E0%AC%B8%E0%AD%8D%E0%AC%B0%E0%AD%8B%E0%AC%A4" title="ବିଦ୍ୟୁତ୍ ସ୍ରୋତ - odia" lang="or" hreflang="or" data-title="ବିଦ୍ୟୁତ୍ ସ୍ରୋତ" data-language-autonym="ଓଡ଼ିଆ" data-language-local-name="odia" class="interlanguage-link-target"><span>ଓଡ଼ିଆ</span></a></li><li class="interlanguage-link interwiki-pa mw-list-item"><a href="https://pa.wikipedia.org/wiki/%E0%A8%AC%E0%A8%BF%E0%A8%9C%E0%A8%B2%E0%A8%88_%E0%A8%95%E0%A8%B0%E0%A9%B0%E0%A8%9F" title="ਬਿਜਲਈ ਕਰੰਟ - punjabi" lang="pa" hreflang="pa" data-title="ਬਿਜਲਈ ਕਰੰਟ" data-language-autonym="ਪੰਜਾਬੀ" data-language-local-name="punjabi" class="interlanguage-link-target"><span>ਪੰਜਾਬੀ</span></a></li><li class="interlanguage-link interwiki-pl mw-list-item"><a href="https://pl.wikipedia.org/wiki/Pr%C4%85d_elektryczny" title="Prąd elektryczny - polacco" lang="pl" hreflang="pl" data-title="Prąd elektryczny" data-language-autonym="Polski" data-language-local-name="polacco" class="interlanguage-link-target"><span>Polski</span></a></li><li class="interlanguage-link interwiki-pms mw-list-item"><a href="https://pms.wikipedia.org/wiki/Corent_el%C3%A9trica" title="Corent elétrica - piemontese" lang="pms" hreflang="pms" data-title="Corent elétrica" data-language-autonym="Piemontèis" data-language-local-name="piemontese" class="interlanguage-link-target"><span>Piemontèis</span></a></li><li class="interlanguage-link interwiki-pnb mw-list-item"><a href="https://pnb.wikipedia.org/wiki/%DA%A9%D8%B1%D9%86%D9%B9" title="کرنٹ - Western Punjabi" lang="pnb" hreflang="pnb" data-title="کرنٹ" data-language-autonym="پنجابی" data-language-local-name="Western Punjabi" class="interlanguage-link-target"><span>پنجابی</span></a></li><li class="interlanguage-link interwiki-ps mw-list-item"><a href="https://ps.wikipedia.org/wiki/%D8%A8%D8%B1%DB%90%DA%9A%D9%86%D8%A7%D9%8A%D9%8A_%D8%AC%D8%B1%D9%8A%D8%A7%D9%86" title="برېښنايي جريان - pashto" lang="ps" hreflang="ps" data-title="برېښنايي جريان" data-language-autonym="پښتو" data-language-local-name="pashto" class="interlanguage-link-target"><span>پښتو</span></a></li><li class="interlanguage-link interwiki-pt mw-list-item"><a href="https://pt.wikipedia.org/wiki/Corrente_el%C3%A9trica" title="Corrente elétrica - portoghese" lang="pt" hreflang="pt" data-title="Corrente elétrica" data-language-autonym="Português" data-language-local-name="portoghese" class="interlanguage-link-target"><span>Português</span></a></li><li class="interlanguage-link interwiki-qu mw-list-item"><a href="https://qu.wikipedia.org/wiki/Pinchikilla_puriy" title="Pinchikilla puriy - quechua" lang="qu" hreflang="qu" data-title="Pinchikilla puriy" data-language-autonym="Runa Simi" data-language-local-name="quechua" class="interlanguage-link-target"><span>Runa Simi</span></a></li><li class="interlanguage-link interwiki-ro mw-list-item"><a href="https://ro.wikipedia.org/wiki/Curent_electric" title="Curent electric - rumeno" lang="ro" hreflang="ro" data-title="Curent electric" data-language-autonym="Română" data-language-local-name="rumeno" class="interlanguage-link-target"><span>Română</span></a></li><li class="interlanguage-link interwiki-ru mw-list-item"><a href="https://ru.wikipedia.org/wiki/%D0%AD%D0%BB%D0%B5%D0%BA%D1%82%D1%80%D0%B8%D1%87%D0%B5%D1%81%D0%BA%D0%B8%D0%B9_%D1%82%D0%BE%D0%BA" title="Электрический ток - russo" lang="ru" hreflang="ru" data-title="Электрический ток" data-language-autonym="Русский" data-language-local-name="russo" class="interlanguage-link-target"><span>Русский</span></a></li><li class="interlanguage-link interwiki-scn mw-list-item"><a href="https://scn.wikipedia.org/wiki/Currenti_elettrica" title="Currenti elettrica - siciliano" lang="scn" hreflang="scn" data-title="Currenti elettrica" data-language-autonym="Sicilianu" data-language-local-name="siciliano" class="interlanguage-link-target"><span>Sicilianu</span></a></li><li class="interlanguage-link interwiki-sco mw-list-item"><a href="https://sco.wikipedia.org/wiki/Electric_current" title="Electric current - scozzese" lang="sco" hreflang="sco" data-title="Electric current" data-language-autonym="Scots" data-language-local-name="scozzese" class="interlanguage-link-target"><span>Scots</span></a></li><li class="interlanguage-link interwiki-sd mw-list-item"><a href="https://sd.wikipedia.org/wiki/%D8%A8%D8%AC%D9%84%D9%8A%D8%A1%D9%8E_%D8%AC%D9%88_%DA%AA%D8%B1%D9%86%D9%BD" title="بجليءَ جو ڪرنٽ - sindhi" lang="sd" hreflang="sd" data-title="بجليءَ جو ڪرنٽ" data-language-autonym="سنڌي" data-language-local-name="sindhi" class="interlanguage-link-target"><span>سنڌي</span></a></li><li class="interlanguage-link interwiki-sh mw-list-item"><a href="https://sh.wikipedia.org/wiki/Elektri%C4%8Dna_struja" title="Električna struja - serbo-croato" lang="sh" hreflang="sh" data-title="Električna struja" data-language-autonym="Srpskohrvatski / српскохрватски" data-language-local-name="serbo-croato" class="interlanguage-link-target"><span>Srpskohrvatski / српскохрватски</span></a></li><li class="interlanguage-link interwiki-simple mw-list-item"><a href="https://simple.wikipedia.org/wiki/Electric_current" title="Electric current - Simple English" lang="en-simple" hreflang="en-simple" data-title="Electric current" data-language-autonym="Simple English" data-language-local-name="Simple English" class="interlanguage-link-target"><span>Simple English</span></a></li><li class="interlanguage-link interwiki-sk badge-Q70893996 mw-list-item" title=""><a href="https://sk.wikipedia.org/wiki/Pr%C3%BAd_elektr%C3%B3nov_(pohyb_%C4%8Dast%C3%ADc)" title="Prúd elektrónov (pohyb častíc) - slovacco" lang="sk" hreflang="sk" data-title="Prúd elektrónov (pohyb častíc)" data-language-autonym="Slovenčina" data-language-local-name="slovacco" class="interlanguage-link-target"><span>Slovenčina</span></a></li><li class="interlanguage-link interwiki-sl mw-list-item"><a href="https://sl.wikipedia.org/wiki/Elektri%C4%8Dni_tok" title="Električni tok - sloveno" lang="sl" hreflang="sl" data-title="Električni tok" data-language-autonym="Slovenščina" data-language-local-name="sloveno" class="interlanguage-link-target"><span>Slovenščina</span></a></li><li class="interlanguage-link interwiki-sn mw-list-item"><a href="https://sn.wikipedia.org/wiki/Muyerero_weMagetsi" title="Muyerero weMagetsi - shona" lang="sn" hreflang="sn" data-title="Muyerero weMagetsi" data-language-autonym="ChiShona" data-language-local-name="shona" class="interlanguage-link-target"><span>ChiShona</span></a></li><li class="interlanguage-link interwiki-sq mw-list-item"><a href="https://sq.wikipedia.org/wiki/Korrenti_elektrik" title="Korrenti elektrik - albanese" lang="sq" hreflang="sq" data-title="Korrenti elektrik" data-language-autonym="Shqip" data-language-local-name="albanese" class="interlanguage-link-target"><span>Shqip</span></a></li><li class="interlanguage-link interwiki-sr mw-list-item"><a href="https://sr.wikipedia.org/wiki/%D0%95%D0%BB%D0%B5%D0%BA%D1%82%D1%80%D0%B8%D1%87%D0%BD%D0%B0_%D1%81%D1%82%D1%80%D1%83%D1%98%D0%B0" title="Електрична струја - serbo" lang="sr" hreflang="sr" data-title="Електрична струја" data-language-autonym="Српски / srpski" data-language-local-name="serbo" class="interlanguage-link-target"><span>Српски / srpski</span></a></li><li class="interlanguage-link interwiki-su mw-list-item"><a href="https://su.wikipedia.org/wiki/Arus_listrik" title="Arus listrik - sundanese" lang="su" hreflang="su" data-title="Arus listrik" data-language-autonym="Sunda" data-language-local-name="sundanese" class="interlanguage-link-target"><span>Sunda</span></a></li><li class="interlanguage-link interwiki-sv mw-list-item"><a href="https://sv.wikipedia.org/wiki/Elektrisk_str%C3%B6m" title="Elektrisk ström - svedese" lang="sv" hreflang="sv" data-title="Elektrisk ström" data-language-autonym="Svenska" data-language-local-name="svedese" class="interlanguage-link-target"><span>Svenska</span></a></li><li class="interlanguage-link interwiki-sw mw-list-item"><a href="https://sw.wikipedia.org/wiki/Mkondo_wa_umeme" title="Mkondo wa umeme - swahili" lang="sw" hreflang="sw" data-title="Mkondo wa umeme" data-language-autonym="Kiswahili" data-language-local-name="swahili" class="interlanguage-link-target"><span>Kiswahili</span></a></li><li class="interlanguage-link interwiki-szl mw-list-item"><a href="https://szl.wikipedia.org/wiki/Sztr%C5%AFm" title="Sztrům - slesiano" lang="szl" hreflang="szl" data-title="Sztrům" data-language-autonym="Ślůnski" data-language-local-name="slesiano" class="interlanguage-link-target"><span>Ślůnski</span></a></li><li class="interlanguage-link interwiki-ta mw-list-item"><a href="https://ta.wikipedia.org/wiki/%E0%AE%AE%E0%AE%BF%E0%AE%A9%E0%AF%8D%E0%AE%A9%E0%AF%8B%E0%AE%9F%E0%AF%8D%E0%AE%9F%E0%AE%AE%E0%AF%8D" title="மின்னோட்டம் - tamil" lang="ta" hreflang="ta" data-title="மின்னோட்டம்" data-language-autonym="தமிழ்" data-language-local-name="tamil" class="interlanguage-link-target"><span>தமிழ்</span></a></li><li class="interlanguage-link interwiki-th mw-list-item"><a href="https://th.wikipedia.org/wiki/%E0%B8%81%E0%B8%A3%E0%B8%B0%E0%B9%81%E0%B8%AA%E0%B9%84%E0%B8%9F%E0%B8%9F%E0%B9%89%E0%B8%B2" title="กระแสไฟฟ้า - thailandese" lang="th" hreflang="th" data-title="กระแสไฟฟ้า" data-language-autonym="ไทย" data-language-local-name="thailandese" class="interlanguage-link-target"><span>ไทย</span></a></li><li class="interlanguage-link interwiki-tl mw-list-item"><a href="https://tl.wikipedia.org/wiki/Daloy_ng_kuryente" title="Daloy ng kuryente - tagalog" lang="tl" hreflang="tl" data-title="Daloy ng kuryente" data-language-autonym="Tagalog" data-language-local-name="tagalog" class="interlanguage-link-target"><span>Tagalog</span></a></li><li class="interlanguage-link interwiki-tr mw-list-item"><a href="https://tr.wikipedia.org/wiki/Elektrik_ak%C4%B1m%C4%B1" title="Elektrik akımı - turco" lang="tr" hreflang="tr" data-title="Elektrik akımı" data-language-autonym="Türkçe" data-language-local-name="turco" class="interlanguage-link-target"><span>Türkçe</span></a></li><li class="interlanguage-link interwiki-tt mw-list-item"><a href="https://tt.wikipedia.org/wiki/%D0%AD%D0%BB%D0%B5%D0%BA%D1%82%D1%80_%D0%B0%D0%B3%D1%8B%D0%BC%D1%8B" title="Электр агымы - tataro" lang="tt" hreflang="tt" data-title="Электр агымы" data-language-autonym="Татарча / tatarça" data-language-local-name="tataro" class="interlanguage-link-target"><span>Татарча / tatarça</span></a></li><li class="interlanguage-link interwiki-ug mw-list-item"><a href="https://ug.wikipedia.org/wiki/%D8%AA%D9%88%D9%83_%D8%A6%DB%90%D9%82%D9%89%D9%85%D9%89" title="توك ئېقىمى - uiguro" lang="ug" hreflang="ug" data-title="توك ئېقىمى" data-language-autonym="ئۇيغۇرچە / Uyghurche" data-language-local-name="uiguro" class="interlanguage-link-target"><span>ئۇيغۇرچە / Uyghurche</span></a></li><li class="interlanguage-link interwiki-uk mw-list-item"><a href="https://uk.wikipedia.org/wiki/%D0%95%D0%BB%D0%B5%D0%BA%D1%82%D1%80%D0%B8%D1%87%D0%BD%D0%B8%D0%B9_%D1%81%D1%82%D1%80%D1%83%D0%BC" title="Електричний струм - ucraino" lang="uk" hreflang="uk" data-title="Електричний струм" data-language-autonym="Українська" data-language-local-name="ucraino" class="interlanguage-link-target"><span>Українська</span></a></li><li class="interlanguage-link interwiki-ur mw-list-item"><a href="https://ur.wikipedia.org/wiki/%D8%A8%D8%B1%D9%82%DB%8C_%D8%B1%D9%88" title="برقی رو - urdu" lang="ur" hreflang="ur" data-title="برقی رو" data-language-autonym="اردو" data-language-local-name="urdu" class="interlanguage-link-target"><span>اردو</span></a></li><li class="interlanguage-link interwiki-uz mw-list-item"><a href="https://uz.wikipedia.org/wiki/Elektr_toki" title="Elektr toki - uzbeco" lang="uz" hreflang="uz" data-title="Elektr toki" data-language-autonym="Oʻzbekcha / ўзбекча" data-language-local-name="uzbeco" class="interlanguage-link-target"><span>Oʻzbekcha / ўзбекча</span></a></li><li class="interlanguage-link interwiki-vec mw-list-item"><a href="https://vec.wikipedia.org/wiki/Corente_e%C5%82etrega" title="Corente ełetrega - veneto" lang="vec" hreflang="vec" data-title="Corente ełetrega" data-language-autonym="Vèneto" data-language-local-name="veneto" class="interlanguage-link-target"><span>Vèneto</span></a></li><li class="interlanguage-link interwiki-vep mw-list-item"><a href="https://vep.wikipedia.org/wiki/Elektrine_joksuz" title="Elektrine joksuz - vepso" lang="vep" hreflang="vep" data-title="Elektrine joksuz" data-language-autonym="Vepsän kel’" data-language-local-name="vepso" class="interlanguage-link-target"><span>Vepsän kel’</span></a></li><li class="interlanguage-link interwiki-vi mw-list-item"><a href="https://vi.wikipedia.org/wiki/D%C3%B2ng_%C4%91i%E1%BB%87n" title="Dòng điện - vietnamita" lang="vi" hreflang="vi" data-title="Dòng điện" data-language-autonym="Tiếng Việt" data-language-local-name="vietnamita" class="interlanguage-link-target"><span>Tiếng Việt</span></a></li><li class="interlanguage-link interwiki-vls mw-list-item"><a href="https://vls.wikipedia.org/wiki/Elektrieke_stroom" title="Elektrieke stroom - fiammingo occidentale" lang="vls" hreflang="vls" data-title="Elektrieke stroom" data-language-autonym="West-Vlams" data-language-local-name="fiammingo occidentale" class="interlanguage-link-target"><span>West-Vlams</span></a></li><li class="interlanguage-link interwiki-war mw-list-item"><a href="https://war.wikipedia.org/wiki/Kuryente_elektrisidad" title="Kuryente elektrisidad - waray" lang="war" hreflang="war" data-title="Kuryente elektrisidad" data-language-autonym="Winaray" data-language-local-name="waray" class="interlanguage-link-target"><span>Winaray</span></a></li><li class="interlanguage-link interwiki-wo mw-list-item"><a href="https://wo.wikipedia.org/wiki/Dawaanu_mb%C3%ABj" title="Dawaanu mbëj - wolof" lang="wo" hreflang="wo" data-title="Dawaanu mbëj" data-language-autonym="Wolof" data-language-local-name="wolof" class="interlanguage-link-target"><span>Wolof</span></a></li><li class="interlanguage-link interwiki-wuu mw-list-item"><a href="https://wuu.wikipedia.org/wiki/%E7%94%B5%E6%B5%81" title="电流 - wu" lang="wuu" hreflang="wuu" data-title="电流" data-language-autonym="吴语" data-language-local-name="wu" class="interlanguage-link-target"><span>吴语</span></a></li><li class="interlanguage-link interwiki-xmf mw-list-item"><a href="https://xmf.wikipedia.org/wiki/%E1%83%94%E1%83%9A%E1%83%94%E1%83%A5%E1%83%A2%E1%83%A0%E1%83%A3%E1%83%9A%E1%83%98_%E1%83%93%E1%83%94%E1%83%9C%E1%83%98" title="ელექტრული დენი - mengrelio" lang="xmf" hreflang="xmf" data-title="ელექტრული დენი" data-language-autonym="მარგალური" data-language-local-name="mengrelio" class="interlanguage-link-target"><span>მარგალური</span></a></li><li class="interlanguage-link interwiki-yi mw-list-item"><a href="https://yi.wikipedia.org/wiki/%D7%A2%D7%9C%D7%A2%D7%A7%D7%98%D7%A8%D7%99%D7%A9%D7%A2%D7%A8_%D7%A9%D7%98%D7%A8%D7%90%D7%9D" title="עלעקטרישער שטראם - yiddish" lang="yi" hreflang="yi" data-title="עלעקטרישער שטראם" data-language-autonym="ייִדיש" data-language-local-name="yiddish" class="interlanguage-link-target"><span>ייִדיש</span></a></li><li class="interlanguage-link interwiki-yo mw-list-item"><a href="https://yo.wikipedia.org/wiki/%C3%8Cw%E1%BB%8D%CC%81_%C3%ACtann%C3%A1" title="Ìwọ́ ìtanná - yoruba" lang="yo" hreflang="yo" data-title="Ìwọ́ ìtanná" data-language-autonym="Yorùbá" data-language-local-name="yoruba" class="interlanguage-link-target"><span>Yorùbá</span></a></li><li class="interlanguage-link interwiki-zh mw-list-item"><a href="https://zh.wikipedia.org/wiki/%E7%94%B5%E6%B5%81" title="电流 - cinese" lang="zh" hreflang="zh" data-title="电流" data-language-autonym="中文" data-language-local-name="cinese" class="interlanguage-link-target"><span>中文</span></a></li><li class="interlanguage-link interwiki-zh-classical mw-list-item"><a href="https://zh-classical.wikipedia.org/wiki/%E9%9B%BB%E6%B5%81" title="電流 - cinese classico" lang="lzh" hreflang="lzh" data-title="電流" data-language-autonym="文言" data-language-local-name="cinese classico" class="interlanguage-link-target"><span>文言</span></a></li><li class="interlanguage-link interwiki-zh-min-nan mw-list-item"><a href="https://zh-min-nan.wikipedia.org/wiki/Ti%C4%81n-li%C3%BB" title="Tiān-liû - min nan" lang="nan" hreflang="nan" data-title="Tiān-liû" data-language-autonym="閩南語 / Bân-lâm-gú" data-language-local-name="min nan" class="interlanguage-link-target"><span>閩南語 / Bân-lâm-gú</span></a></li><li class="interlanguage-link interwiki-zh-yue mw-list-item"><a href="https://zh-yue.wikipedia.org/wiki/%E9%9B%BB%E6%B5%81" 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id="siteSub" class="noprint">Da Wikipedia, l'enciclopedia libera.</div> </div> <div id="contentSub"><div id="mw-content-subtitle"></div></div> <div id="mw-content-text" class="mw-body-content"><div class="mw-content-ltr mw-parser-output" lang="it" dir="ltr"><figure class="mw-default-size" typeof="mw:File/Thumb"><a href="/wiki/File:Direzione_convenzionale_della_corrente_elettrica.svg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/0/0c/Direzione_convenzionale_della_corrente_elettrica.svg/310px-Direzione_convenzionale_della_corrente_elettrica.svg.png" decoding="async" width="310" height="123" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/0/0c/Direzione_convenzionale_della_corrente_elettrica.svg/465px-Direzione_convenzionale_della_corrente_elettrica.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/0/0c/Direzione_convenzionale_della_corrente_elettrica.svg/620px-Direzione_convenzionale_della_corrente_elettrica.svg.png 2x" data-file-width="677" data-file-height="269" /></a><figcaption>Rappresentazione del moto di cariche elettriche positive (+) o negative (-) (tipicamente <a href="/wiki/Elettrone" title="Elettrone">elettroni</a>) in un conduttore. Convenzionalmente, il verso della corrente è quello delle cariche positive, e quindi opposto al verso del moto degli elettroni.</figcaption></figure> <p>La <b>corrente elettrica</b>, in <a href="/wiki/Fisica" title="Fisica">fisica</a> ed <a href="/wiki/Elettrotecnica" title="Elettrotecnica">elettrotecnica</a>, indica lo spostamento complessivo delle <a href="/wiki/Carica_elettrica" title="Carica elettrica">cariche elettriche</a>, cioè un qualsiasi moto ordinato definito operativamente come la quantità di <a href="/wiki/Carica_elettrica" title="Carica elettrica">carica elettrica</a> che attraversa una determinata superficie nell'unità di tempo.<sup id="cite_ref-def3_1-0" class="reference"><a href="#cite_note-def3-1"><span class="cite-bracket">[</span>1<span class="cite-bracket">]</span></a></sup> </p> <meta property="mw:PageProp/toc" /> <div class="mw-heading mw-heading2"><h2 id="Descrizione">Descrizione</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Corrente_elettrica&veaction=edit&section=1" title="Modifica la sezione Descrizione" class="mw-editsection-visualeditor"><span>modifica</span></a><span class="mw-editsection-divider"> | </span><a href="/w/index.php?title=Corrente_elettrica&action=edit&section=1" title="Edit section's source code: Descrizione"><span>modifica wikitesto</span></a><span class="mw-editsection-bracket">]</span></span></div> <figure class="mw-default-size" typeof="mw:File/Thumb"><a href="/wiki/File:Amper%C3%ADmetro.png" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/f/f7/Amper%C3%ADmetro.png" decoding="async" width="267" height="182" class="mw-file-element" data-file-width="267" data-file-height="182" /></a><figcaption>Schema di un <a href="/wiki/Circuito_elettrico" title="Circuito elettrico">circuito elettrico</a> in cui è inserito un amperometro (A) per la misurazione della corrente che circola in un ramo del circuito.</figcaption></figure> <p>Con la corrente elettrica ci si riferisce solitamente a cariche negative, gli <a href="/wiki/Elettrone" title="Elettrone">elettroni</a>, che "scorrono" in <a href="/wiki/Conduttore_elettrico" title="Conduttore elettrico">conduttori</a> solidi, solitamente <a href="/wiki/Metallo" title="Metallo">metallici</a>. Ma in altri casi si verifica uno spostamento di carica positiva, come ad esempio <a href="/wiki/Ione" title="Ione">ioni</a> positivi di <a href="/wiki/Elettrolita" title="Elettrolita">soluzioni elettrolitiche</a>. Sia per ragioni storiche, sia dal momento che la direzione del flusso delle cariche dipende dal fatto che esse siano positive o negative, si definisce convenzionalmente il verso della corrente come la direzione del flusso di carica positiva. Tale convenzione si deve a <a href="/wiki/Benjamin_Franklin" title="Benjamin Franklin">Benjamin Franklin</a>. Nelle applicazioni pratiche, comunque, il verso della corrente è importante per il corretto funzionamento dei <a href="/wiki/Circuito_elettronico" title="Circuito elettronico">circuiti elettronici</a>, mentre ha una importanza minore nei <a href="/wiki/Circuito_elettrico" title="Circuito elettrico">circuiti elettrici</a>. </p><p>L'<a href="/wiki/Intensit%C3%A0_di_corrente" title="Intensità di corrente">intensità di corrente</a> elettrica, indicata col simbolo <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle I}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <mi>I</mi> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle I}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/535ea7fc4134a31cbe2251d9d3511374bc41be9f" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.338ex; width:1.172ex; height:2.176ex;" alt="{\displaystyle I}"></span> (una <a href="/wiki/I" title="I">I</a> maiuscola), è assunta come <a href="/wiki/Sistema_internazionale_di_unit%C3%A0_di_misura#Unità_fondamentali" title="Sistema internazionale di unità di misura">grandezza fondamentale</a> nel <a href="/wiki/Sistema_internazionale_di_unit%C3%A0_di_misura" title="Sistema internazionale di unità di misura">sistema internazionale (SI)</a>.<sup id="cite_ref-IUPAC_Gold_Book,_electric_current_2-0" class="reference"><a href="#cite_note-IUPAC_Gold_Book,_electric_current-2"><span class="cite-bracket">[</span>2<span class="cite-bracket">]</span></a></sup> La sua <a href="/wiki/Unit%C3%A0_di_misura" title="Unità di misura">unità di misura</a> è l'<a href="/wiki/Ampere" title="Ampere">ampere</a> (<i>A</i>),<sup id="cite_ref-IUPAC_Gold_Book,_ampere_3-0" class="reference"><a href="#cite_note-IUPAC_Gold_Book,_ampere-3"><span class="cite-bracket">[</span>3<span class="cite-bracket">]</span></a></sup> e da essa si ricava l'unità di misura della <a href="/wiki/Carica_elettrica" title="Carica elettrica">carica elettrica</a>, il <a href="/wiki/Coulomb" title="Coulomb">coulomb</a>, che corrisponde alla quantità di carica trasportata da una corrente con intensità pari ad 1 ampere nell'unità di tempo di 1 secondo (<span class="nowrap"><span data-sort-value="7000100000000000000♠"></span>1 C</span> = <span class="nowrap"><span data-sort-value="7000100000000000000♠"></span>1 A•s</span>).<sup id="cite_ref-4" class="reference"><a href="#cite_note-4"><span class="cite-bracket">[</span>4<span class="cite-bracket">]</span></a></sup> È chiamata così in onore del fisico <a href="/wiki/Andr%C3%A9-Marie_Amp%C3%A8re" title="André-Marie Ampère">André-Marie Ampère</a>. </p><p>L'intensità della corrente elettrica viene generalmente misurata con l'<a href="/wiki/Amperometro" title="Amperometro">amperometro</a>, ma per fare questo concorrono due metodi differenti: un metodo richiede l'interruzione del circuito, che talvolta può essere un inconveniente, mentre l'altro metodo è molto meno invasivo ed utilizza il rilevamento del <a href="/wiki/Campo_magnetico" title="Campo magnetico">campo magnetico</a> generato dal flusso della corrente, ma in questo caso è necessaria una certa quantità di campo, che non sempre è presente in alcuni circuiti a bassa potenza. Gli strumenti usati per quest'ultimo metodo comprendono i sensori a <a href="/wiki/Effetto_Hall" title="Effetto Hall">effetto di Hall</a> o morsetti e <a href="/wiki/Bobina_di_Rogowski" title="Bobina di Rogowski">spire di Rogowski</a>. </p><p>La corrente elettrica costituisce una <a href="/wiki/Grandezza_fisica" title="Grandezza fisica">grandezza fisica</a> di fondamentale importanza nella tecnologia legata alla <a href="/wiki/Teoria_dei_circuiti" title="Teoria dei circuiti">teoria dei circuiti</a>, all'<a href="/wiki/Elettrotecnica" title="Elettrotecnica">elettrotecnica</a> ed all'<a href="/wiki/Elettronica" title="Elettronica">elettronica</a>, avendo un grande numero di applicazioni come ad esempio il trasporto di <a href="/wiki/Energia_elettrica" title="Energia elettrica">energia elettrica</a> oppure di <a href="/wiki/Informazione" title="Informazione">informazioni</a> tramite <a href="/wiki/Segnale_elettrico" title="Segnale elettrico">segnali</a> (ad esempio nelle <a href="/wiki/Comunicazioni_elettriche" title="Comunicazioni elettriche">comunicazioni</a>). </p> <div class="mw-heading mw-heading3"><h3 id="Conduzione_elettrica">Conduzione elettrica</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Corrente_elettrica&veaction=edit&section=2" title="Modifica la sezione Conduzione elettrica" class="mw-editsection-visualeditor"><span>modifica</span></a><span class="mw-editsection-divider"> | </span><a href="/w/index.php?title=Corrente_elettrica&action=edit&section=2" title="Edit section's source code: Conduzione elettrica"><span>modifica wikitesto</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>Una corrente elettrica per fluire necessita di un <a href="/wiki/Conduttore_elettrico" title="Conduttore elettrico">conduttore elettrico</a>, ossia un mezzo in cui è possibile il movimento delle cariche. I conduttori sono formati da un reticolo di cationi in cui è possibile il movimento degli elettroni. In base al conduttore è possibile determinare una <a href="/wiki/Densit%C3%A0_di_carica" title="Densità di carica">densità di carica</a> <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle \rho }"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <mi>ρ</mi> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle \rho }</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/1f7d439671d1289b6a816e6af7a304be40608d64" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.838ex; width:1.202ex; height:2.176ex;" alt="{\displaystyle \rho }"></span> definita come la quantità di carica per ogni unità di volume. Per calcolare il valore della densità di carica è necessario conoscere la carica dell'elettrone <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle e}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <mi>e</mi> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle e}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/cd253103f0876afc68ebead27a5aa9867d927467" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.338ex; width:1.083ex; height:1.676ex;" alt="{\displaystyle e}"></span> e il numero di elettroni per unità di volume <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle n}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <mi>n</mi> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle n}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/a601995d55609f2d9f5e233e36fbe9ea26011b3b" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.338ex; width:1.395ex; height:1.676ex;" alt="{\displaystyle n}"></span>. Considerata la <a href="/wiki/Densit%C3%A0" title="Densità">densità</a> del conduttore <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle d}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <mi>d</mi> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle d}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/e85ff03cbe0c7341af6b982e47e9f90d235c66ab" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.338ex; width:1.216ex; height:2.176ex;" alt="{\displaystyle d}"></span>, la <a href="/wiki/Massa_molare" title="Massa molare">massa molare</a> degli elettroni <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle M_{e}}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <msub> <mi>M</mi> <mrow class="MJX-TeXAtom-ORD"> <mi>e</mi> </mrow> </msub> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle M_{e}}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/e55c1a4cf7fc155c8113a0f9df63986766c25609" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.671ex; width:3.252ex; height:2.509ex;" alt="{\displaystyle M_{e}}"></span> e il <a href="/wiki/Costante_di_Avogadro" title="Costante di Avogadro">numero di elettroni per mole</a> <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle N_{A}}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <msub> <mi>N</mi> <mrow class="MJX-TeXAtom-ORD"> <mi>A</mi> </mrow> </msub> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle N_{A}}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/9fa9233ef6a6a2c0576dbf65490ddb8307fde494" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.671ex; width:3.331ex; height:2.509ex;" alt="{\displaystyle N_{A}}"></span> si ottiene: </p> <dl><dd><span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle \rho =e\,n=e\,{N_{A}d \over M_{e}}}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <mi>ρ</mi> <mo>=</mo> <mi>e</mi> <mspace width="thinmathspace" /> <mi>n</mi> <mo>=</mo> <mi>e</mi> <mspace width="thinmathspace" /> <mrow class="MJX-TeXAtom-ORD"> <mfrac> <mrow> <msub> <mi>N</mi> <mrow class="MJX-TeXAtom-ORD"> <mi>A</mi> </mrow> </msub> <mi>d</mi> </mrow> <msub> <mi>M</mi> <mrow class="MJX-TeXAtom-ORD"> <mi>e</mi> </mrow> </msub> </mfrac> </mrow> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle \rho =e\,n=e\,{N_{A}d \over M_{e}}}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/68a62e653325dcfdf9c04b115a2caf26d5655865" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -2.338ex; width:17.118ex; height:5.843ex;" alt="{\displaystyle \rho =e\,n=e\,{N_{A}d \over M_{e}}}"></span></dd></dl> <p>In elettrotecnica uno dei materiali conduttori più utilizzati è il rame che ha una densità di carica <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle \rho _{\mathrm {Cu} }=13,6\,\mathrm {C/mm^{3}} }"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <msub> <mi>ρ</mi> <mrow class="MJX-TeXAtom-ORD"> <mrow class="MJX-TeXAtom-ORD"> <mi mathvariant="normal">C</mi> <mi mathvariant="normal">u</mi> </mrow> </mrow> </msub> <mo>=</mo> <mn>13</mn> <mo>,</mo> <mn>6</mn> <mspace width="thinmathspace" /> <mrow class="MJX-TeXAtom-ORD"> <mi mathvariant="normal">C</mi> <mrow class="MJX-TeXAtom-ORD"> <mo>/</mo> </mrow> <mi mathvariant="normal">m</mi> <msup> <mi mathvariant="normal">m</mi> <mrow class="MJX-TeXAtom-ORD"> <mn>3</mn> </mrow> </msup> </mrow> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle \rho _{\mathrm {Cu} }=13,6\,\mathrm {C/mm^{3}} }</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/8d0a6ad2bcb98409bdccbf93da89d9a8bac49a41" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.838ex; width:19.308ex; height:3.176ex;" alt="{\displaystyle \rho _{\mathrm {Cu} }=13,6\,\mathrm {C/mm^{3}} }"></span>, un ordine di grandezza comune a tutti i materiali conduttori. </p><p>Nei conduttori il moto degli elettroni è casuale pertanto se non agisce alcun campo elettrico la loro velocità media è nulla, viceversa la presenza di un campo elettrico genera tra due punti del conduttore una <a href="/wiki/Differenza_di_potenziale" title="Differenza di potenziale">differenza di potenziale</a> che induce gli elettroni a muoversi al fine di annullare la <a href="/wiki/Differenza_di_potenziale_elettrico" class="mw-redirect" title="Differenza di potenziale elettrico">tensione</a> e ristabilire l'equilibrio dando così origine a una corrente elettrica. Se al conduttore viene applicato un dispositivo in grado di mantenere una differenza di potenziale (<a href="/wiki/Generatore_di_tensione" title="Generatore di tensione">generatore di tensione</a>) allora il potenziale prende il nome di <a href="/wiki/Forza_elettromotrice" title="Forza elettromotrice">forza elettromotrice</a>.<sup id="cite_ref-5" class="reference"><a href="#cite_note-5"><span class="cite-bracket">[</span>5<span class="cite-bracket">]</span></a></sup> </p><p>In un solido conduttore gli atomi che lo compongono rilasciano degli elettroni di conduzione. Gli elettroni di conduzione sono delocalizzati nel solido e il cui numero è specifico del conduttore considerato, ma può subire piccole variazioni determinate dalla temperatura del solido. A causa del principio di esclusione di Pauli gli elettroni non possono avere tutti la stessa energia, quindi anche allo zero assoluto alcuni elettroni hanno un'energia cinetica il cui livello massimo è detto <a href="/wiki/Energia_di_Fermi" title="Energia di Fermi">energia di Fermi</a>. L'energia di Fermi come l'energia cinetica del più alto livello occupato nello stato fondamentale degli elettroni di conduzione. La velocità del moto casuale degli elettroni dipende dall'energia di Fermi <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle E_{F}}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <msub> <mi>E</mi> <mrow class="MJX-TeXAtom-ORD"> <mi>F</mi> </mrow> </msub> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle E_{F}}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/c11f54775db7f6468779534bdcc4ce0f9054905f" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.671ex; width:3.178ex; height:2.509ex;" alt="{\displaystyle E_{F}}"></span> dell'elettrone di massa <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle m_{e}}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <msub> <mi>m</mi> <mrow class="MJX-TeXAtom-ORD"> <mi>e</mi> </mrow> </msub> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle m_{e}}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/8303b668e94e02d8f3db8c5b3ebd069ca5da9ba5" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.671ex; width:3.039ex; height:2.009ex;" alt="{\displaystyle m_{e}}"></span> attraverso la relazione: </p> <dl><dd><span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle v_{F}={\sqrt {2E_{F} \over m_{e}}}}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <msub> <mi>v</mi> <mrow class="MJX-TeXAtom-ORD"> <mi>F</mi> </mrow> </msub> <mo>=</mo> <mrow class="MJX-TeXAtom-ORD"> <msqrt> <mfrac> <mrow> <mn>2</mn> <msub> <mi>E</mi> <mrow class="MJX-TeXAtom-ORD"> <mi>F</mi> </mrow> </msub> </mrow> <msub> <mi>m</mi> <mrow class="MJX-TeXAtom-ORD"> <mi>e</mi> </mrow> </msub> </mfrac> </msqrt> </mrow> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle v_{F}={\sqrt {2E_{F} \over m_{e}}}}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/d39db2515367aab1e257532fc2819099a9ae0c5d" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -3.171ex; width:13.19ex; height:7.509ex;" alt="{\displaystyle v_{F}={\sqrt {2E_{F} \over m_{e}}}}"></span></dd></dl> <p>Nel rame l'energia di Fermi ha un valore di <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle E_{F_{\mathrm {Cu} }}=7,03\,\mathrm {eV} }"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <msub> <mi>E</mi> <mrow class="MJX-TeXAtom-ORD"> <msub> <mi>F</mi> <mrow class="MJX-TeXAtom-ORD"> <mrow class="MJX-TeXAtom-ORD"> <mi mathvariant="normal">C</mi> <mi mathvariant="normal">u</mi> </mrow> </mrow> </msub> </mrow> </msub> <mo>=</mo> <mn>7</mn> <mo>,</mo> <mn>03</mn> <mspace width="thinmathspace" /> <mrow class="MJX-TeXAtom-ORD"> <mi mathvariant="normal">e</mi> <mi mathvariant="normal">V</mi> </mrow> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle E_{F_{\mathrm {Cu} }}=7,03\,\mathrm {eV} }</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/8911fbc2e2390e7069e55087e1f9969ceddfb665" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -1.005ex; width:15.656ex; height:2.843ex;" alt="{\displaystyle E_{F_{\mathrm {Cu} }}=7,03\,\mathrm {eV} }"></span> e quindi la velocità di Fermi di <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle v_{F_{\mathrm {Cu} }}=1,57\times 10^{6}\mathrm {m/s} }"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <msub> <mi>v</mi> <mrow class="MJX-TeXAtom-ORD"> <msub> <mi>F</mi> <mrow class="MJX-TeXAtom-ORD"> <mrow class="MJX-TeXAtom-ORD"> <mi mathvariant="normal">C</mi> <mi mathvariant="normal">u</mi> </mrow> </mrow> </msub> </mrow> </msub> <mo>=</mo> <mn>1</mn> <mo>,</mo> <mn>57</mn> <mo>×</mo> <msup> <mn>10</mn> <mrow class="MJX-TeXAtom-ORD"> <mn>6</mn> </mrow> </msup> <mrow class="MJX-TeXAtom-ORD"> <mi mathvariant="normal">m</mi> <mrow class="MJX-TeXAtom-ORD"> <mo>/</mo> </mrow> <mi mathvariant="normal">s</mi> </mrow> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle v_{F_{\mathrm {Cu} }}=1,57\times 10^{6}\mathrm {m/s} }</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/05168b70411ff53223fa030468f87faf22efdb0b" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -1.005ex; width:22.14ex; height:3.343ex;" alt="{\displaystyle v_{F_{\mathrm {Cu} }}=1,57\times 10^{6}\mathrm {m/s} }"></span><sup id="cite_ref-6" class="reference"><a href="#cite_note-6"><span class="cite-bracket">[</span>6<span class="cite-bracket">]</span></a></sup>. </p> <div class="mw-heading mw-heading2"><h2 id="Grandezze_fisiche">Grandezze fisiche</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Corrente_elettrica&veaction=edit&section=3" title="Modifica la sezione Grandezze fisiche" class="mw-editsection-visualeditor"><span>modifica</span></a><span class="mw-editsection-divider"> | </span><a href="/w/index.php?title=Corrente_elettrica&action=edit&section=3" title="Edit section's source code: Grandezze fisiche"><span>modifica wikitesto</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>Una corrente è caratterizzata dall'interazione tra le cariche elettriche presenti nel mezzo conduttore e il campo elettrico. Il movimento di queste cariche è caratterizzato dalla velocità di deriva, una velocità costante e proporzionale al campo elettrico, con cui ne condivide la direzione, ma non il verso che invece dipende dal segno della carica. Dalla velocità di deriva dipendono altre due grandezze: l'intensità di corrente e la densità di corrente. L'intensità di corrente è la quantità carica che attraversa una superficie in un certo periodo di tempo mentre la densità di corrente è il vettore che rappresenta la corrente elettrica che attraversa perpendicolarmente una superficie. </p> <div class="mw-heading mw-heading3"><h3 id="Velocità_di_deriva"><span id="Velocit.C3.A0_di_deriva"></span>Velocità di deriva</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Corrente_elettrica&veaction=edit&section=4" title="Modifica la sezione Velocità di deriva" class="mw-editsection-visualeditor"><span>modifica</span></a><span class="mw-editsection-divider"> | </span><a href="/w/index.php?title=Corrente_elettrica&action=edit&section=4" title="Edit section's source code: Velocità di deriva"><span>modifica wikitesto</span></a><span class="mw-editsection-bracket">]</span></span></div> <style data-mw-deduplicate="TemplateStyles:r130657691">body:not(.skin-minerva) .mw-parser-output .vedi-anche{font-size:95%}</style><style data-mw-deduplicate="TemplateStyles:r139142988">.mw-parser-output .hatnote-content{align-items:center;display:flex}.mw-parser-output .hatnote-icon{flex-shrink:0}.mw-parser-output .hatnote-icon img{display:flex}.mw-parser-output .hatnote-text{font-style:italic}body:not(.skin-minerva) .mw-parser-output .hatnote{border:1px solid #CCC;display:flex;margin:.5em 0;padding:.2em .5em}body:not(.skin-minerva) .mw-parser-output .hatnote-text{padding-left:.5em}body.skin-minerva .mw-parser-output .hatnote-icon{padding-right:8px}body.skin-minerva .mw-parser-output .hatnote-icon img{height:auto;width:16px}body.skin--responsive .mw-parser-output .hatnote a.new{color:#d73333}body.skin--responsive .mw-parser-output .hatnote a.new:visited{color:#a55858}</style> <div class="hatnote noprint vedi-anche"> <div class="hatnote-content"><span class="noviewer hatnote-icon" typeof="mw:File"><span><img src="//upload.wikimedia.org/wikipedia/commons/thumb/8/87/Magnifying_glass_icon_mgx2.svg/18px-Magnifying_glass_icon_mgx2.svg.png" decoding="async" width="18" height="18" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/8/87/Magnifying_glass_icon_mgx2.svg/27px-Magnifying_glass_icon_mgx2.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/8/87/Magnifying_glass_icon_mgx2.svg/36px-Magnifying_glass_icon_mgx2.svg.png 2x" data-file-width="286" data-file-height="280" /></span></span> <span class="hatnote-text">Lo stesso argomento in dettaglio: <b><a href="/wiki/Velocit%C3%A0_di_deriva" title="Velocità di deriva">Velocità di deriva</a></b>.</span></div> </div> <figure class="mw-default-size" typeof="mw:File/Thumb"><a href="/wiki/File:Velocit%C3%A0_di_deriva.svg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/f/fb/Velocit%C3%A0_di_deriva.svg/310px-Velocit%C3%A0_di_deriva.svg.png" decoding="async" width="310" height="82" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/f/fb/Velocit%C3%A0_di_deriva.svg/465px-Velocit%C3%A0_di_deriva.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/f/fb/Velocit%C3%A0_di_deriva.svg/620px-Velocit%C3%A0_di_deriva.svg.png 2x" data-file-width="677" data-file-height="180" /></a><figcaption>Rappresentazione del moto caotico di una carica elettrica negativa (tipicamente un <a href="/wiki/Elettrone" title="Elettrone">elettrone</a>) in un conduttore. La freccia rossa indica il vettore del campo elettrico mentre quella nera la velocità di deriva della carica, in questo caso con verso opposto rispetto a quello del campo.</figcaption></figure> <p>In una corrente su cui agisce un <a href="/wiki/Campo_elettrico" title="Campo elettrico">campo elettrico</a> <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle {\vec {E}}}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <mrow class="MJX-TeXAtom-ORD"> <mrow class="MJX-TeXAtom-ORD"> <mover> <mi>E</mi> <mo stretchy="false">→</mo> </mover> </mrow> </mrow> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle {\vec {E}}}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/2bc18ae485a72f148e85ccbeff2b3dcdd4f5f3f7" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.338ex; width:1.776ex; height:2.843ex;" alt="{\displaystyle {\vec {E}}}"></span> il moto degli elettroni è caratterizzato da una velocità di deriva <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle {\vec {v}}_{d}}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <msub> <mrow class="MJX-TeXAtom-ORD"> <mrow class="MJX-TeXAtom-ORD"> <mover> <mi>v</mi> <mo stretchy="false">→</mo> </mover> </mrow> </mrow> <mrow class="MJX-TeXAtom-ORD"> <mi>d</mi> </mrow> </msub> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle {\vec {v}}_{d}}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/d27401cd62e56dcf71b440c48ef6ea76b977b587" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.671ex; width:2.267ex; height:2.676ex;" alt="{\displaystyle {\vec {v}}_{d}}"></span>, ovvero la media delle velocità dei singoli elettroni lungo la direzione del campo. Su ogni carica <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle e}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <mi>e</mi> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle e}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/cd253103f0876afc68ebead27a5aa9867d927467" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.338ex; width:1.083ex; height:1.676ex;" alt="{\displaystyle e}"></span> della corrente agisce una forza <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle {\vec {F}}=e{\vec {E}}}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <mrow class="MJX-TeXAtom-ORD"> <mrow class="MJX-TeXAtom-ORD"> <mover> <mi>F</mi> <mo stretchy="false">→</mo> </mover> </mrow> </mrow> <mo>=</mo> <mi>e</mi> <mrow class="MJX-TeXAtom-ORD"> <mrow class="MJX-TeXAtom-ORD"> <mover> <mi>E</mi> <mo stretchy="false">→</mo> </mover> </mrow> </mrow> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle {\vec {F}}=e{\vec {E}}}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/03f784bef38ba120c86ad44c2ff60cad942b2d76" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.338ex; width:7.728ex; height:2.843ex;" alt="{\displaystyle {\vec {F}}=e{\vec {E}}}"></span> che per il <a href="/wiki/Secondo_principio_della_dinamica" class="mw-redirect" title="Secondo principio della dinamica">secondo principio della dinamica</a> imprime su ogni carica di massa <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle m}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <mi>m</mi> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle m}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/0a07d98bb302f3856cbabc47b2b9016692e3f7bc" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.338ex; width:2.04ex; height:1.676ex;" alt="{\displaystyle m}"></span> un'accelerazione <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle {\vec {a}}=e{\vec {E}}/m}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <mrow class="MJX-TeXAtom-ORD"> <mrow class="MJX-TeXAtom-ORD"> <mover> <mi>a</mi> <mo stretchy="false">→</mo> </mover> </mrow> </mrow> <mo>=</mo> <mi>e</mi> <mrow class="MJX-TeXAtom-ORD"> <mrow class="MJX-TeXAtom-ORD"> <mover> <mi>E</mi> <mo stretchy="false">→</mo> </mover> </mrow> </mrow> <mrow class="MJX-TeXAtom-ORD"> <mo>/</mo> </mrow> <mi>m</mi> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle {\vec {a}}=e{\vec {E}}/m}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/94c589e1eee7a4bcce80562d5ed5fe9847432f1f" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.838ex; width:10.39ex; height:3.343ex;" alt="{\displaystyle {\vec {a}}=e{\vec {E}}/m}"></span>. </p><p>La velocità di deriva delle cariche però assume un valore costante linearmente dipendente dal campo elettrico, pertanto l'accelerazione non può essere considerata continua. Il moto uniformemente accelerato delle cariche infatti è costantemente interrotto dagli urti che avvengono tra gli elettroni e gli ioni del conduttore e che quindi permettono al flusso di mantenere una velocità costante. Considerata una carica della corrente in movimento è possibile definire un tempo <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle \tau }"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <mi>τ</mi> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle \tau }</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/38a7dcde9730ef0853809fefc18d88771f95206c" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.338ex; width:1.202ex; height:1.676ex;" alt="{\displaystyle \tau }"></span> come la durata del moto di una carica tra due urti successivi. Il valore di <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle \tau }"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <mi>τ</mi> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle \tau }</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/38a7dcde9730ef0853809fefc18d88771f95206c" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.338ex; width:1.202ex; height:1.676ex;" alt="{\displaystyle \tau }"></span> dipende dal <a href="/wiki/Cammino_libero_medio" title="Cammino libero medio">cammino libero medio</a> e dalla velocità di Fermi. Definita la <a href="/wiki/Mobilit%C3%A0_elettrica" title="Mobilità elettrica">mobilità elettrica</a> come <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle \mu =e\tau /m_{e}}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <mi>μ</mi> <mo>=</mo> <mi>e</mi> <mi>τ</mi> <mrow class="MJX-TeXAtom-ORD"> <mo>/</mo> </mrow> <msub> <mi>m</mi> <mrow class="MJX-TeXAtom-ORD"> <mi>e</mi> </mrow> </msub> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle \mu =e\tau /m_{e}}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/1e20ce39264542b846d291a033ab14d9c29d3640" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.838ex; width:10.987ex; height:2.843ex;" alt="{\displaystyle \mu =e\tau /m_{e}}"></span> è possibile esprimere velocità di deriva di una carica attraverso la relazione<sup id="cite_ref-7" class="reference"><a href="#cite_note-7"><span class="cite-bracket">[</span>7<span class="cite-bracket">]</span></a></sup>: </p> <dl><dd><span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle {\vec {v}}_{d}=\mu {\vec {E}}}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <msub> <mrow class="MJX-TeXAtom-ORD"> <mrow class="MJX-TeXAtom-ORD"> <mover> <mi>v</mi> <mo stretchy="false">→</mo> </mover> </mrow> </mrow> <mrow class="MJX-TeXAtom-ORD"> <mi>d</mi> </mrow> </msub> <mo>=</mo> <mi>μ</mi> <mrow class="MJX-TeXAtom-ORD"> <mrow class="MJX-TeXAtom-ORD"> <mover> <mi>E</mi> <mo stretchy="false">→</mo> </mover> </mrow> </mrow> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle {\vec {v}}_{d}=\mu {\vec {E}}}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/346a902352c9452810bf6b27996afad0c9e8a5b6" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.838ex; width:8.543ex; height:3.343ex;" alt="{\displaystyle {\vec {v}}_{d}=\mu {\vec {E}}}"></span></dd></dl> <p>La velocità di deriva di una corrente a <span class="nowrap"><span data-sort-value="7000800000000000000♠"></span>8 <a href="/wiki/Ampere" title="Ampere">A</a></span> in un cavo di rame di sezione <span class="nowrap"><span data-sort-value="6994400000000000000♠"></span>4 <a href="/wiki/Metro_quadrato" title="Metro quadrato">mm²</a></span> è di circa <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle v_{d}=0,147\,\mathrm {mm/s} }"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <msub> <mi>v</mi> <mrow class="MJX-TeXAtom-ORD"> <mi>d</mi> </mrow> </msub> <mo>=</mo> <mn>0</mn> <mo>,</mo> <mn>147</mn> <mspace width="thinmathspace" /> <mrow class="MJX-TeXAtom-ORD"> <mi mathvariant="normal">m</mi> <mi mathvariant="normal">m</mi> <mrow class="MJX-TeXAtom-ORD"> <mo>/</mo> </mrow> <mi mathvariant="normal">s</mi> </mrow> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle v_{d}=0,147\,\mathrm {mm/s} }</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/f1f29bebe3b02013c8ddec6a8b862e3d5edbe884" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.838ex; width:17.339ex; height:2.843ex;" alt="{\displaystyle v_{d}=0,147\,\mathrm {mm/s} }"></span>. La velocità di deriva, quindi la velocità della corrente, è dieci miliardi di volte inferiore alla velocità del moto caotico dell'elettrone<sup id="cite_ref-:0_8-0" class="reference"><a href="#cite_note-:0-8"><span class="cite-bracket">[</span>8<span class="cite-bracket">]</span></a></sup>. </p> <div class="mw-heading mw-heading3"><h3 id="Intensità_di_corrente"><span id="Intensit.C3.A0_di_corrente"></span>Intensità di corrente</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Corrente_elettrica&veaction=edit&section=5" title="Modifica la sezione Intensità di corrente" class="mw-editsection-visualeditor"><span>modifica</span></a><span class="mw-editsection-divider"> | </span><a href="/w/index.php?title=Corrente_elettrica&action=edit&section=5" title="Edit section's source code: Intensità di corrente"><span>modifica wikitesto</span></a><span class="mw-editsection-bracket">]</span></span></div> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r130657691"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r139142988"> <div class="hatnote noprint vedi-anche"> <div class="hatnote-content"><span class="noviewer hatnote-icon" typeof="mw:File"><span><img src="//upload.wikimedia.org/wikipedia/commons/thumb/8/87/Magnifying_glass_icon_mgx2.svg/18px-Magnifying_glass_icon_mgx2.svg.png" decoding="async" width="18" height="18" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/8/87/Magnifying_glass_icon_mgx2.svg/27px-Magnifying_glass_icon_mgx2.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/8/87/Magnifying_glass_icon_mgx2.svg/36px-Magnifying_glass_icon_mgx2.svg.png 2x" data-file-width="286" data-file-height="280" /></span></span> <span class="hatnote-text">Lo stesso argomento in dettaglio: <b><a href="/wiki/Intensit%C3%A0_di_corrente" title="Intensità di corrente">Intensità di corrente</a></b>.</span></div> </div> <figure class="mw-default-size" typeof="mw:File/Thumb"><a href="/wiki/File:Intensit%C3%A0_di_corrente.svg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/9/96/Intensit%C3%A0_di_corrente.svg/310px-Intensit%C3%A0_di_corrente.svg.png" decoding="async" width="310" height="82" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/9/96/Intensit%C3%A0_di_corrente.svg/465px-Intensit%C3%A0_di_corrente.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/9/96/Intensit%C3%A0_di_corrente.svg/620px-Intensit%C3%A0_di_corrente.svg.png 2x" data-file-width="677" data-file-height="180" /></a><figcaption>Rappresentazione di una corrente di <a href="/wiki/Elettrone" title="Elettrone">elettroni</a> in un conduttore. Oltre al vettore del campo elettrico sono indicati il vettore della superficie orientata <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle d{\vec {S}}}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <mi>d</mi> <mrow class="MJX-TeXAtom-ORD"> <mrow class="MJX-TeXAtom-ORD"> <mover> <mi>S</mi> <mo stretchy="false">→</mo> </mover> </mrow> </mrow> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle d{\vec {S}}}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/792a6f7db115a1b44f4838b113e79bdeb4c9e960" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.338ex; width:2.754ex; height:3.009ex;" alt="{\displaystyle d{\vec {S}}}"></span> e la quantità di cariche che hanno attraversato la superficie nel tempo <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle dt}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <mi>d</mi> <mi>t</mi> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle dt}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/ebee76a835701fd1f26047a09855f2ea36bb08fc" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.338ex; width:2.055ex; height:2.176ex;" alt="{\displaystyle dt}"></span></figcaption></figure> <p>Nel <a href="/wiki/Sistema_internazionale_di_unit%C3%A0_di_misura" title="Sistema internazionale di unità di misura">sistema internazionale di unità di misura</a> l'intensità di corrente è una delle sette grandezze fisiche fondamentali<sup id="cite_ref-IUPAC_Gold_Book,_electric_current_2-1" class="reference"><a href="#cite_note-IUPAC_Gold_Book,_electric_current-2"><span class="cite-bracket">[</span>2<span class="cite-bracket">]</span></a></sup>, solitamente indicata con i simboli <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle i}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <mi>i</mi> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle i}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/add78d8608ad86e54951b8c8bd6c8d8416533d20" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.338ex; width:0.802ex; height:2.176ex;" alt="{\displaystyle i}"></span> o <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle I}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <mi>I</mi> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle I}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/535ea7fc4134a31cbe2251d9d3511374bc41be9f" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.338ex; width:1.172ex; height:2.176ex;" alt="{\displaystyle I}"></span> (dall'iniziale del termine francese: <i>Intensité du courant</i>) la sua unità di misura è l'<a href="/wiki/Ampere" title="Ampere">ampere</a>: <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle {\textrm {A}}}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <mrow class="MJX-TeXAtom-ORD"> <mrow class="MJX-TeXAtom-ORD"> <mtext>A</mtext> </mrow> </mrow> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle {\textrm {A}}}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/e8ec0a2db5449fd4229eb656f7293873071569d9" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.338ex; width:1.743ex; height:2.176ex;" alt="{\displaystyle {\textrm {A}}}"></span><sup id="cite_ref-IUPAC_Gold_Book,_ampere_3-1" class="reference"><a href="#cite_note-IUPAC_Gold_Book,_ampere-3"><span class="cite-bracket">[</span>3<span class="cite-bracket">]</span></a></sup>. Sia <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle \Delta q}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <mi mathvariant="normal">Δ</mi> <mi>q</mi> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle \Delta q}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/6e1566066f209ca063e592e50d14daf3499c148d" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.671ex; width:3.005ex; height:2.509ex;" alt="{\displaystyle \Delta q}"></span> la quantità di carica che attraversa una superficie interna a un <a href="/wiki/Conduttore_elettrico" title="Conduttore elettrico">conduttore</a> in un tempo <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle \Delta t}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <mi mathvariant="normal">Δ</mi> <mi>t</mi> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle \Delta t}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/8c28867ecd34e2caed12cf38feadf6a81a7ee542" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.338ex; width:2.775ex; height:2.176ex;" alt="{\displaystyle \Delta t}"></span>, allora l'intensità di corrente è definita dalla relazione<sup id="cite_ref-9" class="reference"><a href="#cite_note-9"><span class="cite-bracket">[</span>9<span class="cite-bracket">]</span></a></sup>: </p> <dl><dd><span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle i=\lim _{\Delta t\to 0}{\Delta q \over \Delta t}={dq \over dt}}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <mi>i</mi> <mo>=</mo> <munder> <mo movablelimits="true" form="prefix">lim</mo> <mrow class="MJX-TeXAtom-ORD"> <mi mathvariant="normal">Δ</mi> <mi>t</mi> <mo stretchy="false">→</mo> <mn>0</mn> </mrow> </munder> <mrow class="MJX-TeXAtom-ORD"> <mfrac> <mrow> <mi mathvariant="normal">Δ</mi> <mi>q</mi> </mrow> <mrow> <mi mathvariant="normal">Δ</mi> <mi>t</mi> </mrow> </mfrac> </mrow> <mo>=</mo> <mrow class="MJX-TeXAtom-ORD"> <mfrac> <mrow> <mi>d</mi> <mi>q</mi> </mrow> <mrow> <mi>d</mi> <mi>t</mi> </mrow> </mfrac> </mrow> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle i=\lim _{\Delta t\to 0}{\Delta q \over \Delta t}={dq \over dt}}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/ce7465720ed6dd8476301ff5b508b6bfd390a96f" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -2.171ex; width:18.777ex; height:5.676ex;" alt="{\displaystyle i=\lim _{\Delta t\to 0}{\Delta q \over \Delta t}={dq \over dt}}"></span></dd></dl> <p>L'intensità di corrente è una grandezza scalare il cui verso è determinato dal segno della carica in movimento<sup id="cite_ref-def3_1-1" class="reference"><a href="#cite_note-def3-1"><span class="cite-bracket">[</span>1<span class="cite-bracket">]</span></a></sup>. </p><p>Considerata una superficie interna al conduttore infinitesima e orientata <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle d{\vec {S}}}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <mi>d</mi> <mrow class="MJX-TeXAtom-ORD"> <mrow class="MJX-TeXAtom-ORD"> <mover> <mi>S</mi> <mo stretchy="false">→</mo> </mover> </mrow> </mrow> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle d{\vec {S}}}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/792a6f7db115a1b44f4838b113e79bdeb4c9e960" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.338ex; width:2.754ex; height:3.009ex;" alt="{\displaystyle d{\vec {S}}}"></span> il cui <a href="/wiki/Versore" title="Versore">versore</a> <a href="/wiki/Normale_(superficie)" title="Normale (superficie)">normale</a> forma un angolo <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle \theta }"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <mi>θ</mi> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle \theta }</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/6e5ab2664b422d53eb0c7df3b87e1360d75ad9af" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.338ex; width:1.09ex; height:2.176ex;" alt="{\displaystyle \theta }"></span> con il <a href="/wiki/Campo_elettrico" title="Campo elettrico">campo elettrico</a> <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle {\vec {E}}}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <mrow class="MJX-TeXAtom-ORD"> <mrow class="MJX-TeXAtom-ORD"> <mover> <mi>E</mi> <mo stretchy="false">→</mo> </mover> </mrow> </mrow> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle {\vec {E}}}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/2bc18ae485a72f148e85ccbeff2b3dcdd4f5f3f7" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.338ex; width:1.776ex; height:2.843ex;" alt="{\displaystyle {\vec {E}}}"></span>, allora la superficie forma il medesimo angolo con la velocità di deriva <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle {\vec {v}}_{d}=\mu {\vec {E}}}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <msub> <mrow class="MJX-TeXAtom-ORD"> <mrow class="MJX-TeXAtom-ORD"> <mover> <mi>v</mi> <mo stretchy="false">→</mo> </mover> </mrow> </mrow> <mrow class="MJX-TeXAtom-ORD"> <mi>d</mi> </mrow> </msub> <mo>=</mo> <mi>μ</mi> <mrow class="MJX-TeXAtom-ORD"> <mrow class="MJX-TeXAtom-ORD"> <mover> <mi>E</mi> <mo stretchy="false">→</mo> </mover> </mrow> </mrow> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle {\vec {v}}_{d}=\mu {\vec {E}}}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/346a902352c9452810bf6b27996afad0c9e8a5b6" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.838ex; width:8.543ex; height:3.343ex;" alt="{\displaystyle {\vec {v}}_{d}=\mu {\vec {E}}}"></span>. In un intervallo di tempo infinitesimo le cariche percorrono uno spazio <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle d{\vec {l}}={\vec {v}}_{d}dt}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <mi>d</mi> <mrow class="MJX-TeXAtom-ORD"> <mrow class="MJX-TeXAtom-ORD"> <mover> <mi>l</mi> <mo stretchy="false">→</mo> </mover> </mrow> </mrow> <mo>=</mo> <msub> <mrow class="MJX-TeXAtom-ORD"> <mrow class="MJX-TeXAtom-ORD"> <mover> <mi>v</mi> <mo stretchy="false">→</mo> </mover> </mrow> </mrow> <mrow class="MJX-TeXAtom-ORD"> <mi>d</mi> </mrow> </msub> <mi>d</mi> <mi>t</mi> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle d{\vec {l}}={\vec {v}}_{d}dt}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/2975ca9bc32ab6e9936eeaf26d46dd7243700278" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.671ex; width:9.925ex; height:3.176ex;" alt="{\displaystyle d{\vec {l}}={\vec {v}}_{d}dt}"></span>, di conseguenza la quantità di carica che attraversa la superficie corrisponde a quella contenuta nel volume <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle dV}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <mi>d</mi> <mi>V</mi> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle dV}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/21c3a0961325e164fddf3f56b30add5bce2f37f0" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.338ex; width:3.003ex; height:2.176ex;" alt="{\displaystyle dV}"></span> dato dal <a href="/wiki/Prodotto_scalare" title="Prodotto scalare">prodotto scalare</a> tra <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle d{\vec {S}}}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <mi>d</mi> <mrow class="MJX-TeXAtom-ORD"> <mrow class="MJX-TeXAtom-ORD"> <mover> <mi>S</mi> <mo stretchy="false">→</mo> </mover> </mrow> </mrow> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle d{\vec {S}}}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/792a6f7db115a1b44f4838b113e79bdeb4c9e960" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.338ex; width:2.754ex; height:3.009ex;" alt="{\displaystyle d{\vec {S}}}"></span> e <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle d{\vec {l}}}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <mi>d</mi> <mrow class="MJX-TeXAtom-ORD"> <mrow class="MJX-TeXAtom-ORD"> <mover> <mi>l</mi> <mo stretchy="false">→</mo> </mover> </mrow> </mrow> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle d{\vec {l}}}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/d54b8bdd6f14694592c33ba9164beb0b4f542ff7" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.338ex; width:2.503ex; height:2.843ex;" alt="{\displaystyle d{\vec {l}}}"></span>. Dalla definizione di <a href="/wiki/Densit%C3%A0_di_carica" title="Densità di carica">densità di carica</a> segue che la quantità di carica è <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle dq=\rho \,dV}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <mi>d</mi> <mi>q</mi> <mo>=</mo> <mi>ρ</mi> <mspace width="thinmathspace" /> <mi>d</mi> <mi>V</mi> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle dq=\rho \,dV}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/a4bfff08da3ca71a76bfccac16f061b416368855" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.838ex; width:9.976ex; height:2.676ex;" alt="{\displaystyle dq=\rho \,dV}"></span>. Per definizione di intensità di corrente si ottiene<sup id="cite_ref-:0_8-1" class="reference"><a href="#cite_note-:0-8"><span class="cite-bracket">[</span>8<span class="cite-bracket">]</span></a></sup>: </p> <dl><dd><span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle di=\rho \,{\vec {v}}_{d}\cdot \,d{\vec {S}}=\rho \,v_{d}\,dS\cos \theta }"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <mi>d</mi> <mi>i</mi> <mo>=</mo> <mi>ρ</mi> <mspace width="thinmathspace" /> <msub> <mrow class="MJX-TeXAtom-ORD"> <mrow class="MJX-TeXAtom-ORD"> <mover> <mi>v</mi> <mo stretchy="false">→</mo> </mover> </mrow> </mrow> <mrow class="MJX-TeXAtom-ORD"> <mi>d</mi> </mrow> </msub> <mo>⋅</mo> <mspace width="thinmathspace" /> <mi>d</mi> <mrow class="MJX-TeXAtom-ORD"> <mrow class="MJX-TeXAtom-ORD"> <mover> <mi>S</mi> <mo stretchy="false">→</mo> </mover> </mrow> </mrow> <mo>=</mo> <mi>ρ</mi> <mspace width="thinmathspace" /> <msub> <mi>v</mi> <mrow class="MJX-TeXAtom-ORD"> <mi>d</mi> </mrow> </msub> <mspace width="thinmathspace" /> <mi>d</mi> <mi>S</mi> <mi>cos</mi> <mo>⁡</mo> <mi>θ</mi> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle di=\rho \,{\vec {v}}_{d}\cdot \,d{\vec {S}}=\rho \,v_{d}\,dS\cos \theta }</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/b093b47113ada7b68c25201c1bdfcb61f949f28a" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.838ex; width:28.779ex; height:3.509ex;" alt="{\displaystyle di=\rho \,{\vec {v}}_{d}\cdot \,d{\vec {S}}=\rho \,v_{d}\,dS\cos \theta }"></span></dd></dl> <p>La corrente elettrica per l'<a href="/wiki/Alimentazione_elettrica" title="Alimentazione elettrica">alimentazione</a> (trasformazioni di energia) viene prodotta almeno in due possibili modalità: 1 - <a href="/wiki/Corrente_continua" title="Corrente continua">corrente continua</a> (CC), che presenta tensione e intensità sempre costante nel tempo ed ha un unico verso di percorrenza con una specifica polarità +/- assegnata (ad esempio, le batterie o le pile). 2 - <a href="/wiki/Corrente_alternata" title="Corrente alternata">corrente alternata</a> (CA), che presenta tensione e intensità periodicamente variabile nel tempo ed ha due versi di percorrenza alternati, ovvero cambia verso di percorrenza in base ad una <a href="/wiki/Frequenza" title="Frequenza">frequenza</a> prestabilita (ad esempio la fornitura elettrica energetica civile da 230V a 50 Hz). </p> <div class="mw-heading mw-heading3"><h3 id="Densità_di_corrente_elettrica"><span id="Densit.C3.A0_di_corrente_elettrica"></span>Densità di corrente elettrica</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Corrente_elettrica&veaction=edit&section=6" title="Modifica la sezione Densità di corrente elettrica" class="mw-editsection-visualeditor"><span>modifica</span></a><span class="mw-editsection-divider"> | </span><a href="/w/index.php?title=Corrente_elettrica&action=edit&section=6" title="Edit section's source code: Densità di corrente elettrica"><span>modifica wikitesto</span></a><span class="mw-editsection-bracket">]</span></span></div> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r130657691"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r139142988"> <div class="hatnote noprint vedi-anche"> <div class="hatnote-content"><span class="noviewer hatnote-icon" typeof="mw:File"><span><img src="//upload.wikimedia.org/wikipedia/commons/thumb/8/87/Magnifying_glass_icon_mgx2.svg/18px-Magnifying_glass_icon_mgx2.svg.png" decoding="async" width="18" height="18" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/8/87/Magnifying_glass_icon_mgx2.svg/27px-Magnifying_glass_icon_mgx2.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/8/87/Magnifying_glass_icon_mgx2.svg/36px-Magnifying_glass_icon_mgx2.svg.png 2x" data-file-width="286" data-file-height="280" /></span></span> <span class="hatnote-text">Lo stesso argomento in dettaglio: <b><a href="/wiki/Densit%C3%A0_di_corrente_elettrica" title="Densità di corrente elettrica">Densità di corrente elettrica</a></b>.</span></div> </div> <figure class="mw-default-size" typeof="mw:File/Thumb"><a href="/wiki/File:Densit%C3%A0_di_corrente.svg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/8/8b/Densit%C3%A0_di_corrente.svg/310px-Densit%C3%A0_di_corrente.svg.png" decoding="async" width="310" height="82" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/8/8b/Densit%C3%A0_di_corrente.svg/465px-Densit%C3%A0_di_corrente.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/8/8b/Densit%C3%A0_di_corrente.svg/620px-Densit%C3%A0_di_corrente.svg.png 2x" data-file-width="677" data-file-height="180" /></a><figcaption>Rappresentazione di una corrente di <a href="/wiki/Elettrone" title="Elettrone">elettroni</a> in un conduttore. Sono indicate la densità di carica <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle \rho }"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <mi>ρ</mi> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle \rho }</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/1f7d439671d1289b6a816e6af7a304be40608d64" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.838ex; width:1.202ex; height:2.176ex;" alt="{\displaystyle \rho }"></span> e la densità di corrente <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle {\vec {j}}}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <mrow class="MJX-TeXAtom-ORD"> <mrow class="MJX-TeXAtom-ORD"> <mover> <mi>j</mi> <mo stretchy="false">→</mo> </mover> </mrow> </mrow> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle {\vec {j}}}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/8ce1ed1de8493f7cc7d856ca5427cf311b1597f1" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.671ex; width:1.094ex; height:3.176ex;" alt="{\displaystyle {\vec {j}}}"></span> con direzione e verso del vettore campo elettrico indicato dalla freccia rossa.</figcaption></figure> <p>In <a href="/wiki/Interazione_elettromagnetica" title="Interazione elettromagnetica">elettromagnetismo</a> la densità di corrente elettrica è il <a href="/wiki/Vettore_(matematica)" title="Vettore (matematica)">vettore</a> il cui <a href="/wiki/Flusso" title="Flusso">flusso</a> attraverso una superficie corrisponde alla corrente elettrica che attraversa tale superficie<sup id="cite_ref-den3_10-0" class="reference"><a href="#cite_note-den3-10"><span class="cite-bracket">[</span>10<span class="cite-bracket">]</span></a></sup>. Solitamente indicata con <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle {\vec {j}}}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <mrow class="MJX-TeXAtom-ORD"> <mrow class="MJX-TeXAtom-ORD"> <mover> <mi>j</mi> <mo stretchy="false">→</mo> </mover> </mrow> </mrow> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle {\vec {j}}}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/8ce1ed1de8493f7cc7d856ca5427cf311b1597f1" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.671ex; width:1.094ex; height:3.176ex;" alt="{\displaystyle {\vec {j}}}"></span>, è misurata secondo il <a href="/wiki/Sistema_internazionale_di_unit%C3%A0_di_misura" title="Sistema internazionale di unità di misura">sistema internazionale di unità di misura</a> in <a href="/wiki/Ampere" title="Ampere">ampere</a> al <a href="/wiki/Metro_quadrato" title="Metro quadrato">metro quadrato</a>: <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle {\textrm {A}}/{\textrm {m}}^{2}}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <mrow class="MJX-TeXAtom-ORD"> <mrow class="MJX-TeXAtom-ORD"> <mtext>A</mtext> </mrow> </mrow> <mrow class="MJX-TeXAtom-ORD"> <mo>/</mo> </mrow> <msup> <mrow class="MJX-TeXAtom-ORD"> <mrow class="MJX-TeXAtom-ORD"> <mtext>m</mtext> </mrow> </mrow> <mrow class="MJX-TeXAtom-ORD"> <mn>2</mn> </mrow> </msup> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle {\textrm {A}}/{\textrm {m}}^{2}}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/07329c577004cf34f9f6698c203fcfc9af4ac5fc" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.838ex; width:5.896ex; height:3.176ex;" alt="{\displaystyle {\textrm {A}}/{\textrm {m}}^{2}}"></span>. Considerata la densità di carica e la velocità di deriva di una corrente, allora la densità di corrente è definita dal vettore: </p> <dl><dd><span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle {\vec {j}}=\rho \,{\vec {v}}_{d}}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <mrow class="MJX-TeXAtom-ORD"> <mrow class="MJX-TeXAtom-ORD"> <mover> <mi>j</mi> <mo stretchy="false">→</mo> </mover> </mrow> </mrow> <mo>=</mo> <mi>ρ</mi> <mspace width="thinmathspace" /> <msub> <mrow class="MJX-TeXAtom-ORD"> <mrow class="MJX-TeXAtom-ORD"> <mover> <mi>v</mi> <mo stretchy="false">→</mo> </mover> </mrow> </mrow> <mrow class="MJX-TeXAtom-ORD"> <mi>d</mi> </mrow> </msub> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle {\vec {j}}=\rho \,{\vec {v}}_{d}}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/67e7b1290aa3f144dbe8aefcdd7a6c546a3dcc17" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.838ex; width:8.049ex; height:3.343ex;" alt="{\displaystyle {\vec {j}}=\rho \,{\vec {v}}_{d}}"></span><sup id="cite_ref-den3_10-1" class="reference"><a href="#cite_note-den3-10"><span class="cite-bracket">[</span>10<span class="cite-bracket">]</span></a></sup></dd></dl> <p>La densità di corrente ha la stessa direzione della velocità di deriva delle cariche e verso che dipende dalla carica del portatore stesso: concorde con la velocità di deriva nel caso di carica positiva, discorde nel caso di carica negativa. Essendo legato alla velocità di deriva allora anche il vettore della densità di corrente è direttamente proporzionale al campo elettrico mediante un fattore <a href="/wiki/Conduttivit%C3%A0_elettrica" title="Conduttività elettrica">conduttività elettrica</a> indicato con <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle \sigma }"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <mi>σ</mi> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle \sigma }</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/59f59b7c3e6fdb1d0365a494b81fb9a696138c36" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.338ex; width:1.33ex; height:1.676ex;" alt="{\displaystyle \sigma }"></span>. Sostituendo la velocità di deriva si ottiene: </p> <dl><dd><span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle {\vec {j}}=\rho \mu {\vec {E}}=\sigma {\vec {E}}}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <mrow class="MJX-TeXAtom-ORD"> <mrow class="MJX-TeXAtom-ORD"> <mover> <mi>j</mi> <mo stretchy="false">→</mo> </mover> </mrow> </mrow> <mo>=</mo> <mi>ρ</mi> <mi>μ</mi> <mrow class="MJX-TeXAtom-ORD"> <mrow class="MJX-TeXAtom-ORD"> <mover> <mi>E</mi> <mo stretchy="false">→</mo> </mover> </mrow> </mrow> <mo>=</mo> <mi>σ</mi> <mrow class="MJX-TeXAtom-ORD"> <mrow class="MJX-TeXAtom-ORD"> <mover> <mi>E</mi> <mo stretchy="false">→</mo> </mover> </mrow> </mrow> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle {\vec {j}}=\rho \mu {\vec {E}}=\sigma {\vec {E}}}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/7ee9234e198d0baf2620537cf78a00af333cf0e2" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.838ex; width:14.775ex; height:3.343ex;" alt="{\displaystyle {\vec {j}}=\rho \mu {\vec {E}}=\sigma {\vec {E}}}"></span></dd></dl> <p>Sostituendo alla conduttività elettrica il suo reciproco, ovvero la <a href="/wiki/Resistivit%C3%A0_elettrica" title="Resistività elettrica">resistività elettrica</a>, si ottiene la formulazione moderna della <a href="/wiki/Legge_di_Ohm" title="Legge di Ohm">legge di Ohm</a>. </p><p>La corrente elettrica attraverso una superficie orientata <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle {\vec {S}}}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <mrow class="MJX-TeXAtom-ORD"> <mrow class="MJX-TeXAtom-ORD"> <mover> <mi>S</mi> <mo stretchy="false">→</mo> </mover> </mrow> </mrow> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle {\vec {S}}}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/c71a6b104c40975c738d5f0e22d445ebd509eb81" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.338ex; width:1.538ex; height:3.009ex;" alt="{\displaystyle {\vec {S}}}"></span> (per esempio attraverso la sezione di un conduttore) è il <a href="/wiki/Flusso" title="Flusso">flusso</a> attraverso la superficie della densità di corrente elettrica:<sup id="cite_ref-den3_10-2" class="reference"><a href="#cite_note-den3-10"><span class="cite-bracket">[</span>10<span class="cite-bracket">]</span></a></sup> dove il vettore superficie ha per modulo la superficie e per versore quello normale della superficie. Dalla definizione di densità di corrente è possibile riscrivere l'espressione dell'intensità di corrente come <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle di={\vec {j}}\cdot d{\vec {S}}}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <mi>d</mi> <mi>i</mi> <mo>=</mo> <mrow class="MJX-TeXAtom-ORD"> <mrow class="MJX-TeXAtom-ORD"> <mover> <mi>j</mi> <mo stretchy="false">→</mo> </mover> </mrow> </mrow> <mo>⋅</mo> <mi>d</mi> <mrow class="MJX-TeXAtom-ORD"> <mrow class="MJX-TeXAtom-ORD"> <mover> <mi>S</mi> <mo stretchy="false">→</mo> </mover> </mrow> </mrow> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle di={\vec {j}}\cdot d{\vec {S}}}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/1ba36c17004f4b422361d41f3fdf624ee9052df6" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.671ex; width:10.644ex; height:3.343ex;" alt="{\displaystyle di={\vec {j}}\cdot d{\vec {S}}}"></span>, ne segue che l'intensità di corrente è data dal flusso del vettore densità di corrente attraverso la superficie orientata <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle {\vec {S}}}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <mrow class="MJX-TeXAtom-ORD"> <mrow class="MJX-TeXAtom-ORD"> <mover> <mi>S</mi> <mo stretchy="false">→</mo> </mover> </mrow> </mrow> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle {\vec {S}}}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/c71a6b104c40975c738d5f0e22d445ebd509eb81" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.338ex; width:1.538ex; height:3.009ex;" alt="{\displaystyle {\vec {S}}}"></span>: </p> <dl><dd><span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle i=\int _{S}{\vec {j}}\cdot d{\vec {S}}=\Phi _{S}({\vec {j}})}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <mi>i</mi> <mo>=</mo> <msub> <mo>∫</mo> <mrow class="MJX-TeXAtom-ORD"> <mi>S</mi> </mrow> </msub> <mrow class="MJX-TeXAtom-ORD"> <mrow class="MJX-TeXAtom-ORD"> <mover> <mi>j</mi> <mo stretchy="false">→</mo> </mover> </mrow> </mrow> <mo>⋅</mo> <mi>d</mi> <mrow class="MJX-TeXAtom-ORD"> <mrow class="MJX-TeXAtom-ORD"> <mover> <mi>S</mi> <mo stretchy="false">→</mo> </mover> </mrow> </mrow> <mo>=</mo> <msub> <mi mathvariant="normal">Φ</mi> <mrow class="MJX-TeXAtom-ORD"> <mi>S</mi> </mrow> </msub> <mo stretchy="false">(</mo> <mrow class="MJX-TeXAtom-ORD"> <mrow class="MJX-TeXAtom-ORD"> <mover> <mi>j</mi> <mo stretchy="false">→</mo> </mover> </mrow> </mrow> <mo stretchy="false">)</mo> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle i=\int _{S}{\vec {j}}\cdot d{\vec {S}}=\Phi _{S}({\vec {j}})}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/f3197b6582ea98974186af9fb26f1ceb2faa5ba4" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -2.338ex; width:21.372ex; height:5.676ex;" alt="{\displaystyle i=\int _{S}{\vec {j}}\cdot d{\vec {S}}=\Phi _{S}({\vec {j}})}"></span></dd></dl> <p>Dalla definizione di intensità di corrente è anche possibile ricavare la <a href="/wiki/Carica_elettrica" title="Carica elettrica">carica elettrica</a> totale <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle q}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <mi>q</mi> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle q}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/06809d64fa7c817ffc7e323f85997f783dbdf71d" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.671ex; width:1.07ex; height:2.009ex;" alt="{\displaystyle q}"></span> che fluisce attraverso la superficie <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle S}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <mi>S</mi> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle S}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/4611d85173cd3b508e67077d4a1252c9c05abca2" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.338ex; width:1.499ex; height:2.176ex;" alt="{\displaystyle S}"></span> nell'intervallo di tempo <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle t}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <mi>t</mi> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle t}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/65658b7b223af9e1acc877d848888ecdb4466560" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.338ex; width:0.84ex; height:2.009ex;" alt="{\displaystyle t}"></span><sup id="cite_ref-:0_8-2" class="reference"><a href="#cite_note-:0-8"><span class="cite-bracket">[</span>8<span class="cite-bracket">]</span></a></sup>: </p> <dl><dd><span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle q=\int _{0}^{t}\int _{S}{\vec {j}}\cdot d{\vec {S}}\,dt}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <mi>q</mi> <mo>=</mo> <msubsup> <mo>∫</mo> <mrow class="MJX-TeXAtom-ORD"> <mn>0</mn> </mrow> <mrow class="MJX-TeXAtom-ORD"> <mi>t</mi> </mrow> </msubsup> <msub> <mo>∫</mo> <mrow class="MJX-TeXAtom-ORD"> <mi>S</mi> </mrow> </msub> <mrow class="MJX-TeXAtom-ORD"> <mrow class="MJX-TeXAtom-ORD"> <mover> <mi>j</mi> <mo stretchy="false">→</mo> </mover> </mrow> </mrow> <mo>⋅</mo> <mi>d</mi> <mrow class="MJX-TeXAtom-ORD"> <mrow class="MJX-TeXAtom-ORD"> <mover> <mi>S</mi> <mo stretchy="false">→</mo> </mover> </mrow> </mrow> <mspace width="thinmathspace" /> <mi>d</mi> <mi>t</mi> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle q=\int _{0}^{t}\int _{S}{\vec {j}}\cdot d{\vec {S}}\,dt}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/3ea150a3d8d43a2d218e8102fac4dd961530350f" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -2.338ex; width:18.787ex; height:6.176ex;" alt="{\displaystyle q=\int _{0}^{t}\int _{S}{\vec {j}}\cdot d{\vec {S}}\,dt}"></span></dd></dl> <div class="mw-heading mw-heading4"><h4 id="Legge_di_conservazione_della_carica_elettrica">Legge di conservazione della carica elettrica</h4><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Corrente_elettrica&veaction=edit&section=7" title="Modifica la sezione Legge di conservazione della carica elettrica" class="mw-editsection-visualeditor"><span>modifica</span></a><span class="mw-editsection-divider"> | </span><a href="/w/index.php?title=Corrente_elettrica&action=edit&section=7" title="Edit section's source code: Legge di conservazione della carica elettrica"><span>modifica wikitesto</span></a><span class="mw-editsection-bracket">]</span></span></div> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r130657691"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r139142988"> <div class="hatnote noprint vedi-anche"> <div class="hatnote-content"><span class="noviewer hatnote-icon" typeof="mw:File"><span><img src="//upload.wikimedia.org/wikipedia/commons/thumb/8/87/Magnifying_glass_icon_mgx2.svg/18px-Magnifying_glass_icon_mgx2.svg.png" decoding="async" width="18" height="18" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/8/87/Magnifying_glass_icon_mgx2.svg/27px-Magnifying_glass_icon_mgx2.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/8/87/Magnifying_glass_icon_mgx2.svg/36px-Magnifying_glass_icon_mgx2.svg.png 2x" data-file-width="286" data-file-height="280" /></span></span> <span class="hatnote-text">Lo stesso argomento in dettaglio: <b><a href="/wiki/Legge_di_conservazione_della_carica_elettrica" title="Legge di conservazione della carica elettrica">Legge di conservazione della carica elettrica</a></b>.</span></div> </div> <p>La legge di conservazione della carica elettrica è rappresentata dall'<a href="/wiki/Equazione_di_continuit%C3%A0" title="Equazione di continuità">equazione di continuità</a> per la <a href="/wiki/Carica_elettrica" title="Carica elettrica">carica elettrica</a>, ed afferma che la carica che fluisce attraverso una superficie chiusa <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle S}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <mi>S</mi> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle S}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/4611d85173cd3b508e67077d4a1252c9c05abca2" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.338ex; width:1.499ex; height:2.176ex;" alt="{\displaystyle S}"></span> è la stessa quantità di carica che entra o esce dal volume <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle V}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <mi>V</mi> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle V}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/af0f6064540e84211d0ffe4dac72098adfa52845" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.338ex; width:1.787ex; height:2.176ex;" alt="{\displaystyle V}"></span> delimitato dalla superficie <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle S}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <mi>S</mi> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle S}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/4611d85173cd3b508e67077d4a1252c9c05abca2" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.338ex; width:1.499ex; height:2.176ex;" alt="{\displaystyle S}"></span>. La quantità di carica che entra o esce dal volume <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle V}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <mi>V</mi> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle V}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/af0f6064540e84211d0ffe4dac72098adfa52845" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.338ex; width:1.787ex; height:2.176ex;" alt="{\displaystyle V}"></span> è fornita dalla derivata temporale dell'integrale su tutto <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle V}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <mi>V</mi> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle V}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/af0f6064540e84211d0ffe4dac72098adfa52845" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.338ex; width:1.787ex; height:2.176ex;" alt="{\displaystyle V}"></span> della densità di carica <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle \rho }"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <mi>ρ</mi> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle \rho }</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/1f7d439671d1289b6a816e6af7a304be40608d64" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.838ex; width:1.202ex; height:2.176ex;" alt="{\displaystyle \rho }"></span>, e la legge di conservazione si esprime quindi dicendo che il flusso <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle \Phi _{S}({\vec {j}})}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <msub> <mi mathvariant="normal">Φ</mi> <mrow class="MJX-TeXAtom-ORD"> <mi>S</mi> </mrow> </msub> <mo stretchy="false">(</mo> <mrow class="MJX-TeXAtom-ORD"> <mrow class="MJX-TeXAtom-ORD"> <mover> <mi>j</mi> <mo stretchy="false">→</mo> </mover> </mrow> </mrow> <mo stretchy="false">)</mo> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle \Phi _{S}({\vec {j}})}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/4c6929b41963206c8ba9593959ae4d18e64027ea" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.838ex; width:5.874ex; height:3.343ex;" alt="{\displaystyle \Phi _{S}({\vec {j}})}"></span> della <a href="/wiki/Densit%C3%A0_di_corrente" class="mw-redirect" title="Densità di corrente">densità di corrente</a> elettrica attraverso la superficie chiusa <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle S}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <mi>S</mi> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle S}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/4611d85173cd3b508e67077d4a1252c9c05abca2" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.338ex; width:1.499ex; height:2.176ex;" alt="{\displaystyle S}"></span> è pari a: </p> <dl><dd><span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle \Phi _{S}({\vec {j}})=-{\frac {\partial }{\partial t}}\int _{V}\rho \,dV}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <msub> <mi mathvariant="normal">Φ</mi> <mrow class="MJX-TeXAtom-ORD"> <mi>S</mi> </mrow> </msub> <mo stretchy="false">(</mo> <mrow class="MJX-TeXAtom-ORD"> <mrow class="MJX-TeXAtom-ORD"> <mover> <mi>j</mi> <mo stretchy="false">→</mo> </mover> </mrow> </mrow> <mo stretchy="false">)</mo> <mo>=</mo> <mo>−</mo> <mrow class="MJX-TeXAtom-ORD"> <mfrac> <mi mathvariant="normal">∂</mi> <mrow> <mi mathvariant="normal">∂</mi> <mi>t</mi> </mrow> </mfrac> </mrow> <msub> <mo>∫</mo> <mrow class="MJX-TeXAtom-ORD"> <mi>V</mi> </mrow> </msub> <mi>ρ</mi> <mspace width="thinmathspace" /> <mi>d</mi> <mi>V</mi> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle \Phi _{S}({\vec {j}})=-{\frac {\partial }{\partial t}}\int _{V}\rho \,dV}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/6f34a09215936f331ca55f1b75a6661d534a9261" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -2.338ex; width:21.929ex; height:5.843ex;" alt="{\displaystyle \Phi _{S}({\vec {j}})=-{\frac {\partial }{\partial t}}\int _{V}\rho \,dV}"></span></dd></dl> <p>considerato che: </p> <dl><dd><span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle \Phi _{S}({\vec {j}})=\int _{S}{\vec {j}}\cdot d{\vec {S}}}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <msub> <mi mathvariant="normal">Φ</mi> <mrow class="MJX-TeXAtom-ORD"> <mi>S</mi> </mrow> </msub> <mo stretchy="false">(</mo> <mrow class="MJX-TeXAtom-ORD"> <mrow class="MJX-TeXAtom-ORD"> <mover> <mi>j</mi> <mo stretchy="false">→</mo> </mover> </mrow> </mrow> <mo stretchy="false">)</mo> <mo>=</mo> <msub> <mo>∫</mo> <mrow class="MJX-TeXAtom-ORD"> <mi>S</mi> </mrow> </msub> <mrow class="MJX-TeXAtom-ORD"> <mrow class="MJX-TeXAtom-ORD"> <mover> <mi>j</mi> <mo stretchy="false">→</mo> </mover> </mrow> </mrow> <mo>⋅</mo> <mi>d</mi> <mrow class="MJX-TeXAtom-ORD"> <mrow class="MJX-TeXAtom-ORD"> <mover> <mi>S</mi> <mo stretchy="false">→</mo> </mover> </mrow> </mrow> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle \Phi _{S}({\vec {j}})=\int _{S}{\vec {j}}\cdot d{\vec {S}}}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/41b138ededf30e5b9b07ee528a29efcd96836eb9" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -2.338ex; width:17.471ex; height:5.676ex;" alt="{\displaystyle \Phi _{S}({\vec {j}})=\int _{S}{\vec {j}}\cdot d{\vec {S}}}"></span></dd></dl> <p>allora utilizzando il <a href="/wiki/Teorema_della_divergenza" title="Teorema della divergenza">teorema della divergenza</a> si ottiene: </p> <dl><dd><span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle \Phi _{S}({\vec {j}})=\int _{S}{\vec {j}}\cdot d{\vec {S}}=\int _{V}\mathbf {\nabla } \cdot {\vec {j}}\,dV=-{\frac {\partial }{\partial t}}\int _{V}\rho \,dV}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <msub> <mi mathvariant="normal">Φ</mi> <mrow class="MJX-TeXAtom-ORD"> <mi>S</mi> </mrow> </msub> <mo stretchy="false">(</mo> <mrow class="MJX-TeXAtom-ORD"> <mrow class="MJX-TeXAtom-ORD"> <mover> <mi>j</mi> <mo stretchy="false">→</mo> </mover> </mrow> </mrow> <mo stretchy="false">)</mo> <mo>=</mo> <msub> <mo>∫</mo> <mrow class="MJX-TeXAtom-ORD"> <mi>S</mi> </mrow> </msub> <mrow class="MJX-TeXAtom-ORD"> <mrow class="MJX-TeXAtom-ORD"> <mover> <mi>j</mi> <mo stretchy="false">→</mo> </mover> </mrow> </mrow> <mo>⋅</mo> <mi>d</mi> <mrow class="MJX-TeXAtom-ORD"> <mrow class="MJX-TeXAtom-ORD"> <mover> <mi>S</mi> <mo stretchy="false">→</mo> </mover> </mrow> </mrow> <mo>=</mo> <msub> <mo>∫</mo> <mrow class="MJX-TeXAtom-ORD"> <mi>V</mi> </mrow> </msub> <mrow class="MJX-TeXAtom-ORD"> <mi mathvariant="normal">∇</mi> </mrow> <mo>⋅</mo> <mrow class="MJX-TeXAtom-ORD"> <mrow class="MJX-TeXAtom-ORD"> <mover> <mi>j</mi> <mo stretchy="false">→</mo> </mover> </mrow> </mrow> <mspace width="thinmathspace" /> <mi>d</mi> <mi>V</mi> <mo>=</mo> <mo>−</mo> <mrow class="MJX-TeXAtom-ORD"> <mfrac> <mi mathvariant="normal">∂</mi> <mrow> <mi mathvariant="normal">∂</mi> <mi>t</mi> </mrow> </mfrac> </mrow> <msub> <mo>∫</mo> <mrow class="MJX-TeXAtom-ORD"> <mi>V</mi> </mrow> </msub> <mi>ρ</mi> <mspace width="thinmathspace" /> <mi>d</mi> <mi>V</mi> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle \Phi _{S}({\vec {j}})=\int _{S}{\vec {j}}\cdot d{\vec {S}}=\int _{V}\mathbf {\nabla } \cdot {\vec {j}}\,dV=-{\frac {\partial }{\partial t}}\int _{V}\rho \,dV}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/dc79bf8814a37fa14ecc34508e68b5ff63bb2785" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -2.338ex; width:47.9ex; height:5.843ex;" alt="{\displaystyle \Phi _{S}({\vec {j}})=\int _{S}{\vec {j}}\cdot d{\vec {S}}=\int _{V}\mathbf {\nabla } \cdot {\vec {j}}\,dV=-{\frac {\partial }{\partial t}}\int _{V}\rho \,dV}"></span></dd></dl> <p>da cui: </p> <dl><dd><span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle \int _{V}\left(\mathbf {\nabla } \cdot {\vec {j}}+{\frac {\partial \rho }{\partial t}}\right)\,dV=0}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <msub> <mo>∫</mo> <mrow class="MJX-TeXAtom-ORD"> <mi>V</mi> </mrow> </msub> <mrow> <mo>(</mo> <mrow> <mrow class="MJX-TeXAtom-ORD"> <mi mathvariant="normal">∇</mi> </mrow> <mo>⋅</mo> <mrow class="MJX-TeXAtom-ORD"> <mrow class="MJX-TeXAtom-ORD"> <mover> <mi>j</mi> <mo stretchy="false">→</mo> </mover> </mrow> </mrow> <mo>+</mo> <mrow class="MJX-TeXAtom-ORD"> <mfrac> <mrow> <mi mathvariant="normal">∂</mi> <mi>ρ</mi> </mrow> <mrow> <mi mathvariant="normal">∂</mi> <mi>t</mi> </mrow> </mfrac> </mrow> </mrow> <mo>)</mo> </mrow> <mspace width="thinmathspace" /> <mi>d</mi> <mi>V</mi> <mo>=</mo> <mn>0</mn> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle \int _{V}\left(\mathbf {\nabla } \cdot {\vec {j}}+{\frac {\partial \rho }{\partial t}}\right)\,dV=0}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/68565d5c0a350a741674897c6420bd9637f8fd01" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -2.505ex; width:25.54ex; height:6.176ex;" alt="{\displaystyle \int _{V}\left(\mathbf {\nabla } \cdot {\vec {j}}+{\frac {\partial \rho }{\partial t}}\right)\,dV=0}"></span></dd></dl> <p>Uguagliando gli integrandi si ottiene così l'equazione di continuità per la carica elettrica in forma locale: </p> <dl><dd><span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle \mathbf {\nabla } \cdot {\vec {j}}+{\frac {\partial \rho }{\partial t}}=0}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <mrow class="MJX-TeXAtom-ORD"> <mi mathvariant="normal">∇</mi> </mrow> <mo>⋅</mo> <mrow class="MJX-TeXAtom-ORD"> <mrow class="MJX-TeXAtom-ORD"> <mover> <mi>j</mi> <mo stretchy="false">→</mo> </mover> </mrow> </mrow> <mo>+</mo> <mrow class="MJX-TeXAtom-ORD"> <mfrac> <mrow> <mi mathvariant="normal">∂</mi> <mi>ρ</mi> </mrow> <mrow> <mi mathvariant="normal">∂</mi> <mi>t</mi> </mrow> </mfrac> </mrow> <mo>=</mo> <mn>0</mn> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle \mathbf {\nabla } \cdot {\vec {j}}+{\frac {\partial \rho }{\partial t}}=0}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/8fb1343fd22137c4006ea7467e582ebd1c7ca80f" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -2.005ex; width:15.166ex; height:5.676ex;" alt="{\displaystyle \mathbf {\nabla } \cdot {\vec {j}}+{\frac {\partial \rho }{\partial t}}=0}"></span></dd></dl> <p>Nel caso stazionario la carica si conserva nel tempo: </p> <dl><dd><span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle {\frac {\partial \rho }{\partial t}}=0}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <mrow class="MJX-TeXAtom-ORD"> <mfrac> <mrow> <mi mathvariant="normal">∂</mi> <mi>ρ</mi> </mrow> <mrow> <mi mathvariant="normal">∂</mi> <mi>t</mi> </mrow> </mfrac> </mrow> <mo>=</mo> <mn>0</mn> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle {\frac {\partial \rho }{\partial t}}=0}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/e0c9f617a0673ac5f483570f9f17d2e190330f60" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -2.005ex; width:7.617ex; height:5.676ex;" alt="{\displaystyle {\frac {\partial \rho }{\partial t}}=0}"></span></dd></dl> <p>e questo implica: </p> <dl><dd><span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle \mathbf {\nabla } \cdot {\vec {j}}=0}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <mrow class="MJX-TeXAtom-ORD"> <mi mathvariant="normal">∇</mi> </mrow> <mo>⋅</mo> <mrow class="MJX-TeXAtom-ORD"> <mrow class="MJX-TeXAtom-ORD"> <mover> <mi>j</mi> <mo stretchy="false">→</mo> </mover> </mrow> </mrow> <mo>=</mo> <mn>0</mn> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle \mathbf {\nabla } \cdot {\vec {j}}=0}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/0c03aad9e534dd4f3bfe035e3e8f559a0f7a848c" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.671ex; width:8.97ex; height:3.176ex;" alt="{\displaystyle \mathbf {\nabla } \cdot {\vec {j}}=0}"></span></dd></dl> <p>In regime stazionario, quindi, il vettore densità di corrente costituisce un <a href="/wiki/Campo_vettoriale_solenoidale" title="Campo vettoriale solenoidale">campo vettoriale solenoidale</a>. Dal punto di vista fisico questo significa che il flusso della densità di corrente è costante, e quindi la corrente elettrica attraverso una qualunque sezione del conduttore è sempre la stessa, indipendentemente dalla sezione considerata. Questo fatto va sotto il nome di prima delle <a href="/wiki/Leggi_di_Kirchhoff" title="Leggi di Kirchhoff">leggi di Kirchhoff</a>.<sup id="cite_ref-11" class="reference"><a href="#cite_note-11"><span class="cite-bracket">[</span>11<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading2"><h2 id="Quadricorrente_elettrica">Quadricorrente elettrica</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Corrente_elettrica&veaction=edit&section=8" title="Modifica la sezione Quadricorrente elettrica" class="mw-editsection-visualeditor"><span>modifica</span></a><span class="mw-editsection-divider"> | </span><a href="/w/index.php?title=Corrente_elettrica&action=edit&section=8" title="Edit section's source code: Quadricorrente elettrica"><span>modifica wikitesto</span></a><span class="mw-editsection-bracket">]</span></span></div> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r130657691"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r139142988"> <div class="hatnote noprint vedi-anche"> <div class="hatnote-content"><span class="noviewer hatnote-icon" typeof="mw:File"><span><img src="//upload.wikimedia.org/wikipedia/commons/thumb/8/87/Magnifying_glass_icon_mgx2.svg/18px-Magnifying_glass_icon_mgx2.svg.png" decoding="async" width="18" height="18" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/8/87/Magnifying_glass_icon_mgx2.svg/27px-Magnifying_glass_icon_mgx2.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/8/87/Magnifying_glass_icon_mgx2.svg/36px-Magnifying_glass_icon_mgx2.svg.png 2x" data-file-width="286" data-file-height="280" /></span></span> <span class="hatnote-text">Lo stesso argomento in dettaglio: <b><a href="/wiki/Quadricorrente" title="Quadricorrente">Quadricorrente</a></b>.</span></div> </div> <p>In <a href="/wiki/Elettrodinamica" title="Elettrodinamica">elettrodinamica</a>, la quadricorrente è un <a href="/wiki/Quadrivettore" title="Quadrivettore">quadrivettore</a> definito come: </p> <dl><dd><span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle j^{\alpha }=\left(\rho c,{\vec {j}}\right)=\left(\rho c,j_{x},j_{y},j_{z}\right)}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <msup> <mi>j</mi> <mrow class="MJX-TeXAtom-ORD"> <mi>α</mi> </mrow> </msup> <mo>=</mo> <mrow> <mo>(</mo> <mrow> <mi>ρ</mi> <mi>c</mi> <mo>,</mo> <mrow class="MJX-TeXAtom-ORD"> <mrow class="MJX-TeXAtom-ORD"> <mover> <mi>j</mi> <mo stretchy="false">→</mo> </mover> </mrow> </mrow> </mrow> <mo>)</mo> </mrow> <mo>=</mo> <mrow> <mo>(</mo> <mrow> <mi>ρ</mi> <mi>c</mi> <mo>,</mo> <msub> <mi>j</mi> <mrow class="MJX-TeXAtom-ORD"> <mi>x</mi> </mrow> </msub> <mo>,</mo> <msub> <mi>j</mi> <mrow class="MJX-TeXAtom-ORD"> <mi>y</mi> </mrow> </msub> <mo>,</mo> <msub> <mi>j</mi> <mrow class="MJX-TeXAtom-ORD"> <mi>z</mi> </mrow> </msub> </mrow> <mo>)</mo> </mrow> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle j^{\alpha }=\left(\rho c,{\vec {j}}\right)=\left(\rho c,j_{x},j_{y},j_{z}\right)}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/477a71654078d73fc38747bd1d98fe533d51cd70" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -1.838ex; margin-left: -0.027ex; width:28.796ex; height:4.843ex;" alt="{\displaystyle j^{\alpha }=\left(\rho c,{\vec {j}}\right)=\left(\rho c,j_{x},j_{y},j_{z}\right)}"></span></dd></dl> <p>dove <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle c}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <mi>c</mi> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle c}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/86a67b81c2de995bd608d5b2df50cd8cd7d92455" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.338ex; width:1.007ex; height:1.676ex;" alt="{\displaystyle c}"></span> è la <a href="/wiki/Velocit%C3%A0_della_luce" title="Velocità della luce">velocità della luce</a>, <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle \rho }"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <mi>ρ</mi> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle \rho }</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/1f7d439671d1289b6a816e6af7a304be40608d64" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.838ex; width:1.202ex; height:2.176ex;" alt="{\displaystyle \rho }"></span> la <a href="/wiki/Densit%C3%A0_di_carica" title="Densità di carica">densità di carica</a> elettrica e il suo prodotto per la velocità <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle {\vec {j}}=\rho {\vec {v}}_{d}}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <mrow class="MJX-TeXAtom-ORD"> <mrow class="MJX-TeXAtom-ORD"> <mover> <mi>j</mi> <mo stretchy="false">→</mo> </mover> </mrow> </mrow> <mo>=</mo> <mi>ρ</mi> <msub> <mrow class="MJX-TeXAtom-ORD"> <mrow class="MJX-TeXAtom-ORD"> <mover> <mi>v</mi> <mo stretchy="false">→</mo> </mover> </mrow> </mrow> <mrow class="MJX-TeXAtom-ORD"> <mi>d</mi> </mrow> </msub> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle {\vec {j}}=\rho {\vec {v}}_{d}}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/f912c26f786724b5bb23a314bcbd67efc661c38d" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.838ex; width:7.662ex; height:3.343ex;" alt="{\displaystyle {\vec {j}}=\rho {\vec {v}}_{d}}"></span> la <a href="/wiki/Densit%C3%A0_di_corrente" class="mw-redirect" title="Densità di corrente">densità di corrente</a>, mentre <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle \alpha }"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <mi>α</mi> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle \alpha }</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/b79333175c8b3f0840bfb4ec41b8072c83ea88d3" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.338ex; width:1.488ex; height:1.676ex;" alt="{\displaystyle \alpha }"></span> denota le dimensioni <a href="/wiki/Spaziotempo" title="Spaziotempo">spaziotemporali</a>. </p><p>La quadricorrente può essere espressa in funzione della <a href="/wiki/Quadrivelocit%C3%A0" title="Quadrivelocità">quadrivelocità</a> <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle v^{\alpha }}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <msup> <mi>v</mi> <mrow class="MJX-TeXAtom-ORD"> <mi>α</mi> </mrow> </msup> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle v^{\alpha }}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/06027346e80c9b411efea33de28ce4abab96b7f1" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.338ex; width:2.412ex; height:2.343ex;" alt="{\displaystyle v^{\alpha }}"></span> come:<sup id="cite_ref-12" class="reference"><a href="#cite_note-12"><span class="cite-bracket">[</span>12<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-13" class="reference"><a href="#cite_note-13"><span class="cite-bracket">[</span>13<span class="cite-bracket">]</span></a></sup> </p> <dl><dd><span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle J^{\alpha }=\rho _{0}v^{\alpha }=\rho {\sqrt {1-{\frac {v^{2}}{c^{2}}}}}v^{\alpha }}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <msup> <mi>J</mi> <mrow class="MJX-TeXAtom-ORD"> <mi>α</mi> </mrow> </msup> <mo>=</mo> <msub> <mi>ρ</mi> <mrow class="MJX-TeXAtom-ORD"> <mn>0</mn> </mrow> </msub> <msup> <mi>v</mi> <mrow class="MJX-TeXAtom-ORD"> <mi>α</mi> </mrow> </msup> <mo>=</mo> <mi>ρ</mi> <mrow class="MJX-TeXAtom-ORD"> <msqrt> <mn>1</mn> <mo>−</mo> <mrow class="MJX-TeXAtom-ORD"> <mfrac> <msup> <mi>v</mi> <mrow class="MJX-TeXAtom-ORD"> <mn>2</mn> </mrow> </msup> <msup> <mi>c</mi> <mrow class="MJX-TeXAtom-ORD"> <mn>2</mn> </mrow> </msup> </mfrac> </mrow> </msqrt> </mrow> <msup> <mi>v</mi> <mrow class="MJX-TeXAtom-ORD"> <mi>α</mi> </mrow> </msup> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle J^{\alpha }=\rho _{0}v^{\alpha }=\rho {\sqrt {1-{\frac {v^{2}}{c^{2}}}}}v^{\alpha }}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/e82c9c586bfc258ebc11aa1841a71d30fe5fb91f" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -3.005ex; width:26.633ex; height:7.509ex;" alt="{\displaystyle J^{\alpha }=\rho _{0}v^{\alpha }=\rho {\sqrt {1-{\frac {v^{2}}{c^{2}}}}}v^{\alpha }}"></span></dd></dl> <p>dove la densità di carica <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle \rho }"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <mi>ρ</mi> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle \rho }</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/1f7d439671d1289b6a816e6af7a304be40608d64" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.838ex; width:1.202ex; height:2.176ex;" alt="{\displaystyle \rho }"></span> è misurata da un osservatore fermo che vede muoversi la corrente, mentre <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle \rho _{0}}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <msub> <mi>ρ</mi> <mrow class="MJX-TeXAtom-ORD"> <mn>0</mn> </mrow> </msub> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle \rho _{0}}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/d9c04a9d26b86af8c6205ba2a6287fd655b6b714" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.838ex; width:2.256ex; height:2.176ex;" alt="{\displaystyle \rho _{0}}"></span> è misurata da un osservatore posto nel sistema di riferimento in moto delle cariche, che si muove ad una velocità <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle v=\|\mathbf {v} \|}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <mi>v</mi> <mo>=</mo> <mo fence="false" stretchy="false">‖</mo> <mrow class="MJX-TeXAtom-ORD"> <mi mathvariant="bold">v</mi> </mrow> <mo fence="false" stretchy="false">‖</mo> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle v=\|\mathbf {v} \|}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/74427d4187e470a3a30bb185619306c1af0beafc" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.838ex; width:7.962ex; height:2.843ex;" alt="{\displaystyle v=\|\mathbf {v} \|}"></span> pari alla norma della componente spaziale di <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle v^{\alpha }}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <msup> <mi>v</mi> <mrow class="MJX-TeXAtom-ORD"> <mi>α</mi> </mrow> </msup> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle v^{\alpha }}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/06027346e80c9b411efea33de28ce4abab96b7f1" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.338ex; width:2.412ex; height:2.343ex;" alt="{\displaystyle v^{\alpha }}"></span>. </p><p>In <a href="/wiki/Relativit%C3%A0_speciale" class="mw-redirect" title="Relatività speciale">relatività speciale</a> la legge di conservazione della carica, che nel limite non relativistico è espressa dall'equazione di continuità, assume la seguente forma tensoriale:<sup id="cite_ref-14" class="reference"><a href="#cite_note-14"><span class="cite-bracket">[</span>14<span class="cite-bracket">]</span></a></sup> </p> <dl><dd><span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle \partial _{\alpha }\cdot j=\partial _{a}j^{a}={\frac {\partial \rho }{\partial t}}+\nabla \cdot {\vec {j}}=0}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <msub> <mi mathvariant="normal">∂</mi> <mrow class="MJX-TeXAtom-ORD"> <mi>α</mi> </mrow> </msub> <mo>⋅</mo> <mi>j</mi> <mo>=</mo> <msub> <mi mathvariant="normal">∂</mi> <mrow class="MJX-TeXAtom-ORD"> <mi>a</mi> </mrow> </msub> <msup> <mi>j</mi> <mrow class="MJX-TeXAtom-ORD"> <mi>a</mi> </mrow> </msup> <mo>=</mo> <mrow class="MJX-TeXAtom-ORD"> <mfrac> <mrow> <mi mathvariant="normal">∂</mi> <mi>ρ</mi> </mrow> <mrow> <mi mathvariant="normal">∂</mi> <mi>t</mi> </mrow> </mfrac> </mrow> <mo>+</mo> <mi mathvariant="normal">∇</mi> <mo>⋅</mo> <mrow class="MJX-TeXAtom-ORD"> <mrow class="MJX-TeXAtom-ORD"> <mover> <mi>j</mi> <mo stretchy="false">→</mo> </mover> </mrow> </mrow> <mo>=</mo> <mn>0</mn> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle \partial _{\alpha }\cdot j=\partial _{a}j^{a}={\frac {\partial \rho }{\partial t}}+\nabla \cdot {\vec {j}}=0}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/d4ac216700a10e84cd755e09070e7214143134ea" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -2.005ex; width:30.915ex; height:5.676ex;" alt="{\displaystyle \partial _{\alpha }\cdot j=\partial _{a}j^{a}={\frac {\partial \rho }{\partial t}}+\nabla \cdot {\vec {j}}=0}"></span></dd></dl> <p>dove <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle \partial _{\alpha }}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <msub> <mi mathvariant="normal">∂</mi> <mrow class="MJX-TeXAtom-ORD"> <mi>α</mi> </mrow> </msub> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle \partial _{\alpha }}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/7eab9f5f18c7860f682fdf1443b92c30cc7e02e6" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.671ex; width:2.519ex; height:2.509ex;" alt="{\displaystyle \partial _{\alpha }}"></span> è il <a href="/wiki/Quadrigradiente" title="Quadrigradiente">quadrigradiente</a>, dato da: </p> <dl><dd><span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle \partial _{\alpha }\ =\left({\frac {1}{c}}{\frac {\partial }{\partial t}},\nabla \right)\qquad \partial _{a}j^{a}=\sum _{i=0}^{3}\partial _{i}j^{i}}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <msub> <mi mathvariant="normal">∂</mi> <mrow class="MJX-TeXAtom-ORD"> <mi>α</mi> </mrow> </msub> <mtext> </mtext> <mo>=</mo> <mrow> <mo>(</mo> <mrow> <mrow class="MJX-TeXAtom-ORD"> <mfrac> <mn>1</mn> <mi>c</mi> </mfrac> </mrow> <mrow class="MJX-TeXAtom-ORD"> <mfrac> <mi mathvariant="normal">∂</mi> <mrow> <mi mathvariant="normal">∂</mi> <mi>t</mi> </mrow> </mfrac> </mrow> <mo>,</mo> <mi mathvariant="normal">∇</mi> </mrow> <mo>)</mo> </mrow> <mspace width="2em" /> <msub> <mi mathvariant="normal">∂</mi> <mrow class="MJX-TeXAtom-ORD"> <mi>a</mi> </mrow> </msub> <msup> <mi>j</mi> <mrow class="MJX-TeXAtom-ORD"> <mi>a</mi> </mrow> </msup> <mo>=</mo> <munderover> <mo>∑</mo> <mrow class="MJX-TeXAtom-ORD"> <mi>i</mi> <mo>=</mo> <mn>0</mn> </mrow> <mrow class="MJX-TeXAtom-ORD"> <mn>3</mn> </mrow> </munderover> <msub> <mi mathvariant="normal">∂</mi> <mrow class="MJX-TeXAtom-ORD"> <mi>i</mi> </mrow> </msub> <msup> <mi>j</mi> <mrow class="MJX-TeXAtom-ORD"> <mi>i</mi> </mrow> </msup> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle \partial _{\alpha }\ =\left({\frac {1}{c}}{\frac {\partial }{\partial t}},\nabla \right)\qquad \partial _{a}j^{a}=\sum _{i=0}^{3}\partial _{i}j^{i}}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/927c9f9458c2071ed8ad7bd238cd2e3e18b0cde3" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -3.005ex; width:37.642ex; height:7.176ex;" alt="{\displaystyle \partial _{\alpha }\ =\left({\frac {1}{c}}{\frac {\partial }{\partial t}},\nabla \right)\qquad \partial _{a}j^{a}=\sum _{i=0}^{3}\partial _{i}j^{i}}"></span></dd></dl> <p>In <a href="/wiki/Relativit%C3%A0_generale" title="Relatività generale">relatività generale</a> la quadricorrente è definita come la <a href="/wiki/Divergenza" title="Divergenza">divergenza</a> del vettore spostamento elettromagnetico, dato da: </p> <dl><dd><span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle {\mathcal {D}}^{\mu \nu }\,=\,{\frac {1}{\mu _{0}}}\,g^{\mu \alpha }\,F_{\alpha \beta }\,g^{\beta \nu }\,{\sqrt {-g}}\qquad j^{\mu }=\partial _{\nu }{\mathcal {D}}^{\mu \nu }}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <msup> <mrow class="MJX-TeXAtom-ORD"> <mrow class="MJX-TeXAtom-ORD"> <mi class="MJX-tex-caligraphic" mathvariant="script">D</mi> </mrow> </mrow> <mrow class="MJX-TeXAtom-ORD"> <mi>μ</mi> <mi>ν</mi> </mrow> </msup> <mspace width="thinmathspace" /> <mo>=</mo> <mspace width="thinmathspace" /> <mrow class="MJX-TeXAtom-ORD"> <mfrac> <mn>1</mn> <msub> <mi>μ</mi> <mrow class="MJX-TeXAtom-ORD"> <mn>0</mn> </mrow> </msub> </mfrac> </mrow> <mspace width="thinmathspace" /> <msup> <mi>g</mi> <mrow class="MJX-TeXAtom-ORD"> <mi>μ</mi> <mi>α</mi> </mrow> </msup> <mspace width="thinmathspace" /> <msub> <mi>F</mi> <mrow class="MJX-TeXAtom-ORD"> <mi>α</mi> <mi>β</mi> </mrow> </msub> <mspace width="thinmathspace" /> <msup> <mi>g</mi> <mrow class="MJX-TeXAtom-ORD"> <mi>β</mi> <mi>ν</mi> </mrow> </msup> <mspace width="thinmathspace" /> <mrow class="MJX-TeXAtom-ORD"> <msqrt> <mo>−</mo> <mi>g</mi> </msqrt> </mrow> <mspace width="2em" /> <msup> <mi>j</mi> <mrow class="MJX-TeXAtom-ORD"> <mi>μ</mi> </mrow> </msup> <mo>=</mo> <msub> <mi mathvariant="normal">∂</mi> <mrow class="MJX-TeXAtom-ORD"> <mi>ν</mi> </mrow> </msub> <msup> <mrow class="MJX-TeXAtom-ORD"> <mrow class="MJX-TeXAtom-ORD"> <mi class="MJX-tex-caligraphic" mathvariant="script">D</mi> </mrow> </mrow> <mrow class="MJX-TeXAtom-ORD"> <mi>μ</mi> <mi>ν</mi> </mrow> </msup> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle {\mathcal {D}}^{\mu \nu }\,=\,{\frac {1}{\mu _{0}}}\,g^{\mu \alpha }\,F_{\alpha \beta }\,g^{\beta \nu }\,{\sqrt {-g}}\qquad j^{\mu }=\partial _{\nu }{\mathcal {D}}^{\mu \nu }}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/21b93df8e0a04f0a101b9588e025ffb98e4a2792" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -2.338ex; width:44.275ex; height:5.676ex;" alt="{\displaystyle {\mathcal {D}}^{\mu \nu }\,=\,{\frac {1}{\mu _{0}}}\,g^{\mu \alpha }\,F_{\alpha \beta }\,g^{\beta \nu }\,{\sqrt {-g}}\qquad j^{\mu }=\partial _{\nu }{\mathcal {D}}^{\mu \nu }}"></span></dd></dl> <div class="mw-heading mw-heading2"><h2 id="Pericolosità_della_corrente"><span id="Pericolosit.C3.A0_della_corrente"></span>Pericolosità della corrente</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Corrente_elettrica&veaction=edit&section=9" title="Modifica la sezione Pericolosità della corrente" class="mw-editsection-visualeditor"><span>modifica</span></a><span class="mw-editsection-divider"> | </span><a href="/w/index.php?title=Corrente_elettrica&action=edit&section=9" title="Edit section's source code: Pericolosità della corrente"><span>modifica wikitesto</span></a><span class="mw-editsection-bracket">]</span></span></div> <figure class="mw-default-size" typeof="mw:File/Thumb"><a href="/wiki/File:IEC_TS_60479-1_electric_shock_graph.svg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/7/7f/IEC_TS_60479-1_electric_shock_graph.svg/220px-IEC_TS_60479-1_electric_shock_graph.svg.png" decoding="async" width="220" height="138" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/7/7f/IEC_TS_60479-1_electric_shock_graph.svg/330px-IEC_TS_60479-1_electric_shock_graph.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/7/7f/IEC_TS_60479-1_electric_shock_graph.svg/440px-IEC_TS_60479-1_electric_shock_graph.svg.png 2x" data-file-width="512" data-file-height="320" /></a><figcaption>Grafico in scala logaritmica dell'effetto della corrente alternata I di durata T passante dalla mano sinistra ai piedi, come indicato nella norma IEC 60479-1.<sup id="cite_ref-15" class="reference"><a href="#cite_note-15"><span class="cite-bracket">[</span>15<span class="cite-bracket">]</span></a></sup><br />AC-1: non percepibile.<br />AC-2: percepibile ma senza reazioni muscolari.<br />AC-3: contrazione muscolare con effetti reversibili.<br />AC-4: possibili effetti irreversibili.<br />AC-4.1: fino al 5% di probabilità di fibrillazione ventricolare.<br />AC-4.2: 5-50% di probabilità di fibrillazione ventricolare.<br />AC-4.3: oltre al 50% di probabilità di fibrillazione ventricolare.</figcaption></figure> <p>La soglia di percezione umana dell'intensità di corrente elettrica è circa di <span class="nowrap"><span data-sort-value="6996500000000000000♠"></span>0,5 mA</span> in modalità di <a href="/wiki/Corrente_alternata" title="Corrente alternata">corrente alternata</a> a frequenza di <span class="nowrap"><span data-sort-value="7006599584916000000♠"></span>50-60 Hz</span> e di <span class="nowrap"><span data-sort-value="6997200000000000000♠"></span>2 mA</span> in <a href="/wiki/Corrente_continua" title="Corrente continua">corrente continua</a>. Si deve anche tenere conto che l'effetto di una determinata corrente elettrica varia non solo per l'intensità, ma anche per il tempo di persistenza. </p><p>Se teoricamente la tensione non è di per sé rilevante negli effetti sull'uomo, per essere attraversati da una corrente occorre comunque una tensione minima e questo implica che sotto i <span class="nowrap"><span data-sort-value="7001500000000000000♠"></span>50 Vac</span> circa non si corrono rischi. </p><p>Con intensità di corrente maggiori a quelle specificate si producono nel corpo umano i seguenti effetti: </p> <ul><li><a href="/wiki/Contrazione_tetanica" title="Contrazione tetanica">Tetanizzazione muscolare</a>: i muscoli sottoposti a una corrente elettrica subiscono una sequenza di stimoli elettrici. Non riuscendo a contrarsi e rilassarsi con la frequenza della corrente, i muscoli restano contratti permanentemente. Tale circostanza è particolarmente grave quando un oggetto in tensione viene impugnato, poiché la tetanizzazione paralizza i muscoli impedendone il rilascio. La massima corrente per la quale si riesce a lasciare la presa viene chiamata corrente di rilascio e si aggira sui <span class="nowrap"><span data-sort-value="6998100000000000000♠"></span>10-30 mA</span> a frequenza industriale. La contrazione muscolare si interrompe quando finisce il passaggio della corrente.</li> <li><a href="/w/index.php?title=Arresto_respiratorio&action=edit&redlink=1" class="new" title="Arresto respiratorio (la pagina non esiste)">Arresto respiratorio</a>: tetanizzazione dei muscoli respiratori quando il contatto interessa la regione toracico-polmonare. Comporta <a href="/wiki/Ipossia" title="Ipossia">ipossia</a> quindi danni al cervello dopo pochi minuti.</li> <li><a href="/wiki/Fibrillazione_ventricolare" title="Fibrillazione ventricolare">Fibrillazione ventricolare</a>: un'intensità di corrente alternata sufficientemente elevata (><span class="nowrap"><span data-sort-value="6998500000000000000♠"></span>50 mA</span>) che interessi la regione toracica può provocare la perdita di coordinamento dei muscoli cardiaci, così il cuore non riesce più a pompare sangue causando ipossia e danni al cervello (per raggiungere un'intensità del genere è necessaria un'alta tensione).</li> <li><a href="/wiki/Arresto_cardiaco" title="Arresto cardiaco">Arresto cardiaco</a>: se la corrente interessa il <a href="/wiki/Torace" title="Torace">torace</a>, può fermare il <a href="/wiki/Cuore" title="Cuore">cuore</a>, provocando un <a href="/wiki/Arresto_cardiaco" title="Arresto cardiaco">arresto cardiaco</a>.</li> <li><a href="/wiki/Ustione" title="Ustione">Ustione</a>: sono dovute all'elevata densità di corrente elettrica tra cute e conduttore in tensione che, per <a href="/wiki/Effetto_Joule" title="Effetto Joule">effetto Joule</a>, porta ad elevate temperature ed è quindi capace di provocare gravi ustioni.</li></ul> <p>Si definisce soglia media di pericolosità (p) per una intensità di corrente pari a: </p> <dl><dd><span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle I_{p}=I_{0}+{q \over \Delta t}}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <msub> <mi>I</mi> <mrow class="MJX-TeXAtom-ORD"> <mi>p</mi> </mrow> </msub> <mo>=</mo> <msub> <mi>I</mi> <mrow class="MJX-TeXAtom-ORD"> <mn>0</mn> </mrow> </msub> <mo>+</mo> <mrow class="MJX-TeXAtom-ORD"> <mfrac> <mi>q</mi> <mrow> <mi mathvariant="normal">Δ</mi> <mi>t</mi> </mrow> </mfrac> </mrow> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle I_{p}=I_{0}+{q \over \Delta t}}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/ef0e7de4c77ffba05de283a39207c3bc0c4ff936" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -2.005ex; width:13.71ex; height:5.009ex;" alt="{\displaystyle I_{p}=I_{0}+{q \over \Delta t}}"></span></dd></dl> <p>dove <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle I_{p}}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <msub> <mi>I</mi> <mrow class="MJX-TeXAtom-ORD"> <mi>p</mi> </mrow> </msub> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle I_{p}}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/3226e9ad60e659391806720213f9c5f6123a70f8" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -1.005ex; width:2.082ex; height:2.843ex;" alt="{\displaystyle I_{p}}"></span> è l'intensità di corrente pericolosa e <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle \Delta t}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <mi mathvariant="normal">Δ</mi> <mi>t</mi> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle \Delta t}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/8c28867ecd34e2caed12cf38feadf6a81a7ee542" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.338ex; width:2.775ex; height:2.176ex;" alt="{\displaystyle \Delta t}"></span> il tempo di permanenza. Essa individua il limite al di sotto del quale la corrente è percepibile ma non pericolosa. Al di sopra di esso la corrente deve considerarsi potenzialmente pericolosa. </p><p>I parametri dell'equazione si possono assumere, a frequenza industriale: </p> <dl><dd><span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle I_{0}=10\div 30\,\mathrm {mA} \qquad Q=10\,\mathrm {mC} }"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <msub> <mi>I</mi> <mrow class="MJX-TeXAtom-ORD"> <mn>0</mn> </mrow> </msub> <mo>=</mo> <mn>10</mn> <mo>÷</mo> <mn>30</mn> <mspace width="thinmathspace" /> <mrow class="MJX-TeXAtom-ORD"> <mi mathvariant="normal">m</mi> <mi mathvariant="normal">A</mi> </mrow> <mspace width="2em" /> <mi>Q</mi> <mo>=</mo> <mn>10</mn> <mspace width="thinmathspace" /> <mrow class="MJX-TeXAtom-ORD"> <mi mathvariant="normal">m</mi> <mi mathvariant="normal">C</mi> </mrow> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle I_{0}=10\div 30\,\mathrm {mA} \qquad Q=10\,\mathrm {mC} }</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/0b4e6bc80f1c5a1323fe74986d77bbb940e090a7" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.671ex; width:32.64ex; height:2.509ex;" alt="{\displaystyle I_{0}=10\div 30\,\mathrm {mA} \qquad Q=10\,\mathrm {mC} }"></span></dd></dl> <p>Per quanto riguarda i limiti di tensione, il corpo umano presenta prevalentemente un comportamento resistivo: la tensione <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle U_{p}=R_{u}\cdot I_{p}}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <msub> <mi>U</mi> <mrow class="MJX-TeXAtom-ORD"> <mi>p</mi> </mrow> </msub> <mo>=</mo> <msub> <mi>R</mi> <mrow class="MJX-TeXAtom-ORD"> <mi>u</mi> </mrow> </msub> <mo>⋅</mo> <msub> <mi>I</mi> <mrow class="MJX-TeXAtom-ORD"> <mi>p</mi> </mrow> </msub> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle U_{p}=R_{u}\cdot I_{p}}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/f287e0d3e17847792fe8592e19866c737ef2c924" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -1.005ex; width:12.443ex; height:2.843ex;" alt="{\displaystyle U_{p}=R_{u}\cdot I_{p}}"></span>, che corrisponde alla corrente pericolosa, è di difficile definizione perché la resistenza del corpo può variare in un campo molto ampio, dipendendo da molteplici fattori quali i punti di contatto, l'estensione del contatto, la pressione, lo spessore della pelle e il suo grado di umidità. Si assume <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle R_{u}>2\,k\Omega }"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <msub> <mi>R</mi> <mrow class="MJX-TeXAtom-ORD"> <mi>u</mi> </mrow> </msub> <mo>></mo> <mn>2</mn> <mspace width="thinmathspace" /> <mi>k</mi> <mi mathvariant="normal">Ω</mi> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle R_{u}>2\,k\Omega }</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/3877834b98847b51b76408c25b48bcf753fa7614" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.671ex; width:10.474ex; height:2.509ex;" alt="{\displaystyle R_{u}>2\,k\Omega }"></span>, per questo motivo non vengono ritenute pericolose tensioni sinusoidali con valore efficace U < <span class="nowrap"><span data-sort-value="7001500000000000000♠"></span>50 V</span> e tensioni continue con U < <span class="nowrap"><span data-sort-value="7002120000000000000♠"></span>120 V</span>, applicate per un tempo illimitato. </p><p>Una persona può venire a contatto con parti in tensione, e quindi subire gli effetti del passaggio di corrente mediante <a href="/wiki/Contatto_diretto" class="mw-redirect" title="Contatto diretto">contatto diretto</a> oppure <a href="/wiki/Contatto_indiretto" class="mw-redirect" title="Contatto indiretto">contatto indiretto</a>. Quindi per evitare ciò si devono attuare delle contromisure imposte dalla norma vigente (norme <a href="/wiki/Comitato_elettrotecnico_italiano" title="Comitato elettrotecnico italiano">CEI</a>). </p><p>La protezione contro i <a href="/wiki/Contatto_diretto" class="mw-redirect" title="Contatto diretto">contatti diretti</a> si attua prevenendo i contatti accidentali con le parti in tensione: </p> <ul><li>isolamento delle parti attive con materiale isolante non removibile,</li> <li>involucri o barriere tali da impedire ogni contatto con le parti in tensione,</li> <li>ostacoli o distanziatori,</li> <li><a href="/wiki/Interruttore_differenziale" title="Interruttore differenziale">interruttori differenziali</a> ad alta sensibilità, con correnti differenziali di soglia di Is ≤<span class="nowrap"><span data-sort-value="6998300000000000000♠"></span>30 mA</span></li></ul> <p>La protezione contro i <a href="/wiki/Contatto_indiretto" class="mw-redirect" title="Contatto indiretto">contatti indiretti</a> si realizza nei seguenti modi: </p> <ul><li><a href="/wiki/Messa_a_terra" title="Messa a terra">Messa a terra</a> delle masse,</li> <li>Interruzione automatica dell'alimentazione tramite <a href="/wiki/Interruttore_differenziale" title="Interruttore differenziale">interruttori differenziali</a>,</li> <li>Doppio isolamento delle apparecchiature,</li> <li>Separazione elettrica</li></ul> <p>Schema riassuntivo degli effetti della corrente per tempi di contatto prolungato: </p> <table class="wikitable" cellspacing="0"> <tbody><tr> <th>Valori di corrente</th> <th>Definizione</th> <th>Effetti </th></tr> <tr> <td><span class="nowrap"><span data-sort-value="6997100000000000000♠"></span>1-3 mA</span></td> <td>Soglia di percezione</td> <td>Non si hanno rischi o pericoli per la salute. </td></tr> <tr> <td><span class="nowrap"><span data-sort-value="6997300000000000000♠"></span>3-10 mA</span></td> <td>Elettrificazione</td> <td>Produce una sensazione di formicolio più o meno forte e può provocare movimenti riflessi. </td></tr> <tr> <td><span class="nowrap"><span data-sort-value="6998100000000000000♠"></span>10 mA</span></td> <td>Tetanizzazione</td> <td>Si hanno contrazioni muscolari. Se la parte in tensione è stata afferrata con la mano si può avere paralisi dei muscoli, rendendo difficile il distacco. </td></tr> <tr> <td><span class="nowrap"><span data-sort-value="6998250000000000000♠"></span>25 mA</span></td> <td>Difficoltà respiratorie</td> <td>Si hanno a causa della contrazione di muscoli addetti alla respirazione, e del passaggio di corrente per i centri nervosi che sovrintendono alla funzione respiratoria. </td></tr> <tr> <td><span class="nowrap"><span data-sort-value="6998250000000000000♠"></span>25-30 mA</span></td> <td>Asfissia</td> <td>La tetanizzazione dei muscoli della respirazione, può essere tale da provocare la morte per asfissia. </td></tr> <tr> <td><span class="nowrap"><span data-sort-value="6998600000000000000♠"></span>60-75 mA</span></td> <td>Fibrillazione</td> <td>Se la corrente attraversa il cuore può alterarne il regolare funzionamento, provocando una contrazione irregolare e disordinata delle fibre cardiache che può portare alla morte. </td></tr></tbody></table> <div class="mw-heading mw-heading2"><h2 id="Note">Note</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Corrente_elettrica&veaction=edit&section=10" title="Modifica la sezione Note" class="mw-editsection-visualeditor"><span>modifica</span></a><span class="mw-editsection-divider"> | </span><a href="/w/index.php?title=Corrente_elettrica&action=edit&section=10" title="Edit section's source code: Note"><span>modifica wikitesto</span></a><span class="mw-editsection-bracket">]</span></span></div> <div class="mw-references-wrap mw-references-columns"><ol class="references"> <li id="cite_note-def3-1"><span class="mw-cite-backlink"><b>^</b> <sup><i><a href="#cite_ref-def3_1-0">a</a></i></sup> <sup><i><a href="#cite_ref-def3_1-1">b</a></i></sup></span> <span class="reference-text"><cite class="citation cita" style="font-style:normal"><a href="#CITEREFmencuccini">Mencuccini, Silvestrini</a>, Pag. 169</cite>.</span> </li> <li id="cite_note-IUPAC_Gold_Book,_electric_current-2"><span class="mw-cite-backlink"><b>^</b> <sup><i><a href="#cite_ref-IUPAC_Gold_Book,_electric_current_2-0">a</a></i></sup> <sup><i><a href="#cite_ref-IUPAC_Gold_Book,_electric_current_2-1">b</a></i></sup></span> <span class="reference-text">(<span style="font-weight:bolder; font-size:80%"><abbr title="inglese">EN</abbr></span>) <a rel="nofollow" class="external text" href="http://goldbook.iupac.org/E01927.html">IUPAC Gold Book, "electric current"</a></span> </li> <li id="cite_note-IUPAC_Gold_Book,_ampere-3"><span class="mw-cite-backlink"><b>^</b> <sup><i><a href="#cite_ref-IUPAC_Gold_Book,_ampere_3-0">a</a></i></sup> <sup><i><a href="#cite_ref-IUPAC_Gold_Book,_ampere_3-1">b</a></i></sup></span> <span class="reference-text">(<span style="font-weight:bolder; font-size:80%"><abbr title="inglese">EN</abbr></span>) <a rel="nofollow" class="external text" href="http://goldbook.iupac.org/A00300.html">IUPAC Gold Book, "ampere"</a></span> </li> <li id="cite_note-4"><a href="#cite_ref-4"><b>^</b></a> <span class="reference-text">(<span style="font-weight:bolder; font-size:80%"><abbr title="inglese">EN</abbr></span>) <a rel="nofollow" class="external text" href="http://goldbook.iupac.org/C01365.html">IUPAC Gold Book, "coulomb"</a></span> </li> <li id="cite_note-5"><a href="#cite_ref-5"><b>^</b></a> <span class="reference-text"><cite class="citation cita" style="font-style:normal"><a href="#CITEREFMazzoldi,_Nigro,_Voci">Mazzoldi, Nigro, Voci</a>, pp. 161-162</cite>.</span> </li> <li id="cite_note-6"><a href="#cite_ref-6"><b>^</b></a> <span class="reference-text"><cite class="citation cita" style="font-style:normal"><a href="#CITEREFMazzoldi,_Nigro,_Voci">Mazzoldi, Nigro, Voci</a>, pp. 738-740</cite>.</span> </li> <li id="cite_note-7"><a href="#cite_ref-7"><b>^</b></a> <span class="reference-text"><cite class="citation cita" style="font-style:normal"><a href="#CITEREFmencuccini">Mencuccini, Silvestrini</a>, Pag. 172</cite>.</span> </li> <li id="cite_note-:0-8"><span class="mw-cite-backlink"><b>^</b> <sup><i><a href="#cite_ref-:0_8-0">a</a></i></sup> <sup><i><a href="#cite_ref-:0_8-1">b</a></i></sup> <sup><i><a href="#cite_ref-:0_8-2">c</a></i></sup></span> <span class="reference-text"><cite class="citation cita" style="font-style:normal"><a href="#CITEREFMazzoldi,_Nigro,_Voci">Mazzoldi, Nigro, Voci</a>, pp. 164-170</cite>.</span> </li> <li id="cite_note-9"><a href="#cite_ref-9"><b>^</b></a> <span class="reference-text"><cite class="citation libro" style="font-style:normal"> Paolo Mazzoldi, Massimo Nigro, Cesare Voci, <span style="font-style:italic;">Fisica (Volume II)</span>, EdiSES Editore, 2001, <a href="/wiki/ISBN" title="ISBN">ISBN</a> <a href="/wiki/Speciale:RicercaISBN/88-7959-152-5" title="Speciale:RicercaISBN/88-7959-152-5">88-7959-152-5</a>.</cite>p.164</span> </li> <li id="cite_note-den3-10"><span class="mw-cite-backlink"><b>^</b> <sup><i><a href="#cite_ref-den3_10-0">a</a></i></sup> <sup><i><a href="#cite_ref-den3_10-1">b</a></i></sup> <sup><i><a href="#cite_ref-den3_10-2">c</a></i></sup></span> <span class="reference-text"><cite class="citation cita" style="font-style:normal"><a href="#CITEREFmencuccini">Mencuccini, Silvestrini</a>, Pag. 173</cite>.</span> </li> <li id="cite_note-11"><a href="#cite_ref-11"><b>^</b></a> <span class="reference-text"><cite class="citation cita" style="font-style:normal"><a href="#CITEREFmencuccini">Mencuccini, Silvestrini</a>, pp. 175-177</cite>.</span> </li> <li id="cite_note-12"><a href="#cite_ref-12"><b>^</b></a> <span class="reference-text">Roald K. Wangsness, Electromagnetic Fields, 2nd edition (1986), p. 518, 519</span> </li> <li id="cite_note-13"><a href="#cite_ref-13"><b>^</b></a> <span class="reference-text">Melvin Schwartz, Principles of Electrodynamics, Dover edition (1987), p. 122, 123</span> </li> <li id="cite_note-14"><a href="#cite_ref-14"><b>^</b></a> <span class="reference-text"><cite class="citation cita" style="font-style:normal"><a href="#CITEREFJackson">Jackson</a>, Pag. 554</cite>.</span> </li> <li id="cite_note-15"><a href="#cite_ref-15"><b>^</b></a> <span class="reference-text"><cite class="citation pubblicazione" style="font-style:normal"> Weineng Wang, Zhiqiang Wang e Xiao Peng, <a rel="nofollow" class="external text" href="https://web.archive.org/web/20141108110449/http://papersub.ivypub.org/Global/DownloadService.aspx?PARAMS=Sm91cm5hbElEXjM3OF5JRF4xNDAzOQ_0_0"><span style="font-style:italic;">Effects of the Earth Current Frequency and Distortion on Residual Current Devices</span></a>, in <span style="font-style:italic;">Scientific Journal of Control Engineering</span>, vol. 3, n. 6, Dicembre 2013, pp. 417-422 <small>(archiviato dall'<abbr title="http://papersub.ivypub.org/Global/DownloadService.aspx?PARAMS=Sm91cm5hbElEXjM3OF5JRF4xNDAzOQ_0_0">url originale</abbr> l'8 novembre 2014)</small>.</cite></span> </li> </ol></div> <div class="mw-heading mw-heading2"><h2 id="Bibliografia">Bibliografia</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Corrente_elettrica&veaction=edit&section=11" title="Modifica la sezione Bibliografia" class="mw-editsection-visualeditor"><span>modifica</span></a><span class="mw-editsection-divider"> | </span><a href="/w/index.php?title=Corrente_elettrica&action=edit&section=11" title="Edit section's source code: Bibliografia"><span>modifica wikitesto</span></a><span class="mw-editsection-bracket">]</span></span></div> <ul><li><cite id="CITEREFmencuccini" class="citation libro" style="font-style:normal"> Corrado Mencuccini, Vittorio Silvestrini, <span style="font-style:italic;">Fisica II</span>, Napoli, Liguori Editore, 2010, <a href="/wiki/ISBN" title="ISBN">ISBN</a> <a href="/wiki/Speciale:RicercaISBN/978-88-207-1633-2" title="Speciale:RicercaISBN/978-88-207-1633-2">978-88-207-1633-2</a>.</cite></li> <li><cite id="CITEREFMazzoldi,_Nigro,_Voci" class="citation libro" style="font-style:normal"> Paolo Mazzoldi, Massimo Nigro, Cesare Voci, <span style="font-style:italic;">Fisica</span>, vol. 2, EdiSES Editore, 2001, <a href="/wiki/ISBN" title="ISBN">ISBN</a> <a href="/wiki/Speciale:RicercaISBN/88-7959-152-5" title="Speciale:RicercaISBN/88-7959-152-5">88-7959-152-5</a>.</cite></li> <li><cite id="CITEREFJackson" class="citation libro" style="font-style:normal">(<span style="font-weight:bolder; font-size:80%"><abbr title="inglese">EN</abbr></span>) John D Jackson, <a rel="nofollow" class="external text" href="https://archive.org/details/classicalelectro0000jack_e8g9"><span style="font-style:italic;">Classical Electrodynamics</span></a>, 3rd Edition, Wiley, 1999, <a href="/wiki/ISBN" title="ISBN">ISBN</a> <a href="/wiki/Speciale:RicercaISBN/0-471-30932-X" title="Speciale:RicercaISBN/0-471-30932-X">0-471-30932-X</a>.</cite></li></ul> <div class="mw-heading mw-heading2"><h2 id="Voci_correlate">Voci correlate</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Corrente_elettrica&veaction=edit&section=12" title="Modifica la sezione Voci correlate" class="mw-editsection-visualeditor"><span>modifica</span></a><span class="mw-editsection-divider"> | </span><a href="/w/index.php?title=Corrente_elettrica&action=edit&section=12" title="Edit section's source code: Voci correlate"><span>modifica wikitesto</span></a><span class="mw-editsection-bracket">]</span></span></div> <div class="colonne"> <ul><li><a href="/wiki/Campo_elettrico" title="Campo elettrico">Campo elettrico</a></li> <li><a href="/wiki/Campo_magnetico" title="Campo magnetico">Campo magnetico</a></li> <li><a href="/wiki/Carica_di_un_condensatore" title="Carica di un condensatore">Carica di un condensatore</a></li> <li><a href="/wiki/Conduttivit%C3%A0_elettrica" title="Conduttività elettrica">Conduttività elettrica</a></li> <li><a href="/wiki/Corrente_alternata" title="Corrente alternata">Corrente alternata</a></li> <li><a href="/wiki/Corrente_continua" title="Corrente continua">Corrente continua</a></li> <li><a href="/wiki/Differenza_di_potenziale_elettrico" class="mw-redirect" title="Differenza di potenziale elettrico">Differenza di potenziale elettrico</a></li> <li><a href="/wiki/Guerra_delle_correnti" title="Guerra delle correnti">Guerra delle correnti</a></li> <li><a href="/wiki/Densit%C3%A0_di_corrente_elettrica" title="Densità di corrente elettrica">Densità di corrente elettrica</a></li> <li><a href="/wiki/Equazione_di_continuit%C3%A0" title="Equazione di continuità">Equazione di continuità</a></li> <li><a href="/wiki/Elettricit%C3%A0" title="Elettricità">Elettricità</a></li> <li><a href="/wiki/Generatore_di_corrente" title="Generatore di corrente">Generatore di corrente</a></li> <li><a href="/wiki/Carica_elettrica" title="Carica elettrica">Carica elettrica</a></li> <li><a href="/wiki/Impianto_elettrico" title="Impianto elettrico">Impianto elettrico</a></li> <li><a href="/wiki/Legge_di_Ohm" title="Legge di Ohm">Legge di Ohm</a></li> <li><a href="/wiki/Potenza_elettrica" title="Potenza elettrica">Potenza elettrica</a></li> <li><a href="/wiki/Resistenza_elettrica" title="Resistenza elettrica">Resistenza elettrica</a></li> <li><a href="/wiki/Quadricorrente" title="Quadricorrente">Quadricorrente</a></li> <li><a href="/wiki/Sovracorrente" title="Sovracorrente">Sovracorrente</a></li> <li><a href="/wiki/Tensione_elettrica" title="Tensione elettrica">Tensione elettrica</a></li></ul> </div> <div class="mw-heading mw-heading2"><h2 id="Altri_progetti">Altri progetti</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Corrente_elettrica&veaction=edit&section=13" title="Modifica la sezione Altri progetti" class="mw-editsection-visualeditor"><span>modifica</span></a><span class="mw-editsection-divider"> | </span><a href="/w/index.php?title=Corrente_elettrica&action=edit&section=13" title="Edit section's source code: Altri progetti"><span>modifica wikitesto</span></a><span class="mw-editsection-bracket">]</span></span></div> <div id="interProject" class="toccolours" style="display: none; clear: both; margin-top: 2em"><p id="sisterProjects" style="background-color: #efefef; color: black; font-weight: bold; margin: 0"><span>Altri progetti</span></p><ul title="Collegamenti verso gli altri progetti Wikimedia"> <li class="" title=""><a href="https://it.wikiversity.org/wiki/Corrente_elettrica" class="extiw" title="v:Corrente elettrica">Wikiversità</a></li> <li class="" title=""><span class="plainlinks" title="commons:Category:Electric current"><a class="external text" href="https://commons.wikimedia.org/wiki/Category:Electric_current?uselang=it">Wikimedia Commons</a></span></li></ul></div> <ul><li><span typeof="mw:File"><a href="https://it.wikiversity.org/wiki/" title="Collabora a Wikiversità"><img alt="Collabora a Wikiversità" src="//upload.wikimedia.org/wikipedia/commons/thumb/0/0b/Wikiversity_logo_2017.svg/18px-Wikiversity_logo_2017.svg.png" decoding="async" width="18" height="15" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/0/0b/Wikiversity_logo_2017.svg/27px-Wikiversity_logo_2017.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/0/0b/Wikiversity_logo_2017.svg/36px-Wikiversity_logo_2017.svg.png 2x" data-file-width="626" data-file-height="512" /></a></span> <a href="https://it.wikiversity.org/wiki/" class="extiw" title="v:">Wikiversità</a> contiene risorse sulla <b><a href="https://it.wikiversity.org/wiki/Corrente_elettrica" class="extiw" title="v:Corrente elettrica">corrente elettrica</a></b></li> <li><span typeof="mw:File"><a href="https://commons.wikimedia.org/wiki/?uselang=it" title="Collabora a Wikimedia Commons"><img alt="Collabora a Wikimedia Commons" src="//upload.wikimedia.org/wikipedia/commons/thumb/4/4a/Commons-logo.svg/18px-Commons-logo.svg.png" decoding="async" width="18" height="24" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/4/4a/Commons-logo.svg/27px-Commons-logo.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/4/4a/Commons-logo.svg/36px-Commons-logo.svg.png 2x" data-file-width="1024" data-file-height="1376" /></a></span> <span class="plainlinks"><a class="external text" href="https://commons.wikimedia.org/wiki/?uselang=it">Wikimedia Commons</a></span> contiene immagini o altri file sulla <b><span class="plainlinks"><a class="external text" href="https://commons.wikimedia.org/wiki/Category:Electric_current?uselang=it">corrente elettrica</a></span></b></li></ul> <div class="mw-heading mw-heading2"><h2 id="Collegamenti_esterni">Collegamenti esterni</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Corrente_elettrica&veaction=edit&section=14" title="Modifica la sezione Collegamenti esterni" class="mw-editsection-visualeditor"><span>modifica</span></a><span class="mw-editsection-divider"> | </span><a href="/w/index.php?title=Corrente_elettrica&action=edit&section=14" title="Edit section's source code: Collegamenti esterni"><span>modifica wikitesto</span></a><span class="mw-editsection-bracket">]</span></span></div> <ul><li class="mw-empty-elt"></li> <li><cite id="CITEREFTreccani.it" class="citation web" style="font-style:normal"> <a rel="nofollow" class="external text" href="https://www.treccani.it/enciclopedia/corrente-elettrica"><span style="font-style:italic;">corrènte elèttrica</span></a>, su <span style="font-style:italic;">Treccani.it – Enciclopedie on line</span>, <a href="/wiki/Istituto_dell%27Enciclopedia_Italiana" title="Istituto dell'Enciclopedia Italiana">Istituto dell'Enciclopedia Italiana</a>.</cite> <span class="mw-valign-text-top noprint" typeof="mw:File/Frameless"><a href="https://www.wikidata.org/wiki/Q11651#P3365" title="Modifica su Wikidata"><img alt="Modifica su Wikidata" src="//upload.wikimedia.org/wikipedia/commons/thumb/7/73/Blue_pencil.svg/10px-Blue_pencil.svg.png" decoding="async" width="10" height="10" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/7/73/Blue_pencil.svg/15px-Blue_pencil.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/7/73/Blue_pencil.svg/20px-Blue_pencil.svg.png 2x" data-file-width="600" data-file-height="600" /></a></span></li> <li><cite id="CITEREFBritannica.com" class="citation web" style="font-style:normal">(<span style="font-weight:bolder; font-size:80%"><abbr title="inglese">EN</abbr></span>) <a rel="nofollow" class="external text" href="https://www.britannica.com/science/electric-current"><span style="font-style:italic;">electric current</span></a>, su <span style="font-style:italic;"><a href="/wiki/Enciclopedia_Britannica" title="Enciclopedia Britannica">Enciclopedia Britannica</a></span>, Encyclopædia Britannica, Inc.</cite> <span class="mw-valign-text-top noprint" typeof="mw:File/Frameless"><a href="https://www.wikidata.org/wiki/Q11651#P1417" title="Modifica su Wikidata"><img alt="Modifica su Wikidata" src="//upload.wikimedia.org/wikipedia/commons/thumb/7/73/Blue_pencil.svg/10px-Blue_pencil.svg.png" decoding="async" width="10" height="10" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/7/73/Blue_pencil.svg/15px-Blue_pencil.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/7/73/Blue_pencil.svg/20px-Blue_pencil.svg.png 2x" data-file-width="600" data-file-height="600" /></a></span></li> <li>(<span style="font-weight:bolder; font-size:80%"><abbr title="inglese">EN</abbr></span>) <a rel="nofollow" class="external text" href="https://www.allaboutcircuits.com/">Allaboutcircuits.com</a>, a useful site introducing electricity and electronics</li></ul> <style data-mw-deduplicate="TemplateStyles:r140554510">.mw-parser-output .CdA{border:1px solid #aaa;width:100%;margin:auto;font-size:90%;padding:2px}.mw-parser-output .CdA th{background-color:#f2f2f2;font-weight:bold;width:20%}@media screen{html.skin-theme-clientpref-night .mw-parser-output .CdA{border-color:#54595D}html.skin-theme-clientpref-night .mw-parser-output .CdA th{background-color:#202122}}@media screen and (prefers-color-scheme:dark){html.skin-theme-clientpref-os .mw-parser-output .CdA{border-color:#54595D}html.skin-theme-clientpref-os .mw-parser-output .CdA th{background-color:#202122}}</style><table class="CdA"><tbody><tr><th><a href="/wiki/Aiuto:Controllo_di_autorit%C3%A0" title="Aiuto:Controllo di autorità">Controllo di autorità</a></th><td><a href="/wiki/Nuovo_soggettario" title="Nuovo soggettario">Thesaurus BNCF</a> <span class="uid"><a rel="nofollow" class="external text" href="https://thes.bncf.firenze.sbn.it/termine.php?id=13309">13309</a></span><span style="font-weight:bold;"> ·</span> <a href="/wiki/Library_of_Congress_Control_Number" title="Library of Congress Control Number">LCCN</a> <span class="uid">(<span style="font-weight:bolder; font-size:80%"><abbr title="inglese">EN</abbr></span>) <a rel="nofollow" class="external text" href="http://id.loc.gov/authorities/subjects/sh85041640">sh85041640</a></span><span style="font-weight:bold;"> ·</span> <a href="/wiki/Gemeinsame_Normdatei" title="Gemeinsame Normdatei">GND</a> <span class="uid">(<span style="font-weight:bolder; font-size:80%"><abbr title="tedesco">DE</abbr></span>) <a rel="nofollow" class="external text" href="https://d-nb.info/gnd/4070745-3">4070745-3</a></span><span style="font-weight:bold;"> ·</span> <a href="/wiki/Biblioteca_nazionale_di_Francia" title="Biblioteca nazionale di Francia">BNF</a> <span class="uid">(<span style="font-weight:bolder; font-size:80%"><abbr title="francese">FR</abbr></span>) <a rel="nofollow" class="external text" href="https://catalogue.bnf.fr/ark:/12148/cb11976973f">cb11976973f</a> <a rel="nofollow" class="external text" href="https://data.bnf.fr/ark:/12148/cb11976973f">(data)</a></span><span style="font-weight:bold;"> ·</span> <a href="/wiki/Biblioteca_nazionale_di_Israele" title="Biblioteca nazionale di Israele">J9U</a> <span class="uid">(<span style="font-weight:bolder; font-size:80%"><abbr title="inglese">EN</abbr>, <abbr title="ebraico">HE</abbr></span>) <a rel="nofollow" class="external text" href="http://olduli.nli.org.il/F/?func=find-b&local_base=NLX10&find_code=UID&request=987007535942505171">987007535942505171</a></span><span style="font-weight:bold;"> ·</span> <a href="/wiki/Biblioteca_della_Dieta_nazionale_del_Giappone" title="Biblioteca della Dieta nazionale del Giappone">NDL</a> <span class="uid">(<span style="font-weight:bolder; font-size:80%"><abbr title="inglese">EN</abbr>, <abbr title="giapponese">JA</abbr></span>) <a rel="nofollow" class="external text" href="https://id.ndl.go.jp/auth/ndlna/00561414">00561414</a></span></td></tr></tbody></table> <div class="noprint" style="width:100%; padding: 3px 0; display: flex; flex-wrap: wrap; row-gap: 4px; column-gap: 8px; box-sizing: border-box;"><div style="flex-basis: calc( 100% / 3 - 8px * 2/3 );"><style data-mw-deduplicate="TemplateStyles:r140555418">.mw-parser-output .itwiki-template-occhiello{width:100%;line-height:25px;border:1px solid #CCF;background-color:#F0EEFF;box-sizing:border-box}.mw-parser-output .itwiki-template-occhiello-progetto{background-color:#FAFAFA}@media screen{html.skin-theme-clientpref-night .mw-parser-output .itwiki-template-occhiello{background-color:#202122;border-color:#54595D}html.skin-theme-clientpref-night .mw-parser-output .itwiki-template-occhiello-progetto{background-color:#282929}}@media screen and (prefers-color-scheme:dark){html.skin-theme-clientpref-os .mw-parser-output .itwiki-template-occhiello{background-color:#202122;border-color:#54595D}html.skin-theme-clientpref-os .mw-parser-output .itwiki-template-occhiello-progetto{background-color:#282929}}</style><div class="itwiki-template-occhiello"><span class="noviewer" typeof="mw:File"><a href="/wiki/File:Bar_magnet.jpg" class="mw-file-description" title="Elettromagnetismo"><img alt=" " src="//upload.wikimedia.org/wikipedia/commons/thumb/d/d8/Bar_magnet.jpg/25px-Bar_magnet.jpg" decoding="async" width="25" height="19" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/d/d8/Bar_magnet.jpg/38px-Bar_magnet.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/d/d8/Bar_magnet.jpg/50px-Bar_magnet.jpg 2x" data-file-width="2048" data-file-height="1536" /></a></span> <b><a href="/wiki/Portale:Elettromagnetismo" title="Portale:Elettromagnetismo">Portale Elettromagnetismo</a></b></div></div><div style="flex-basis: calc( 100% / 3 - 8px * 2/3 );"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r140555418"><div class="itwiki-template-occhiello"><span class="noviewer" typeof="mw:File"><a href="/wiki/File:Im-jabber.png" class="mw-file-description" title="Elettrotecnica"><img alt=" " src="//upload.wikimedia.org/wikipedia/commons/thumb/1/1e/Im-jabber.png/25px-Im-jabber.png" decoding="async" width="25" height="25" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/1/1e/Im-jabber.png/38px-Im-jabber.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/1/1e/Im-jabber.png/50px-Im-jabber.png 2x" data-file-width="128" data-file-height="128" /></a></span> <b><a href="/wiki/Portale:Elettrotecnica" title="Portale:Elettrotecnica">Portale Elettrotecnica</a></b></div></div><div style="flex-basis: calc( 100% / 3 - 8px * 2/3 );"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r140555418"><div class="itwiki-template-occhiello"><span class="noviewer" typeof="mw:File"><a href="/wiki/File:Nuvola_apps_katomic.svg" class="mw-file-description" title="Fisica"><img alt=" " src="//upload.wikimedia.org/wikipedia/commons/thumb/5/55/Nuvola_apps_katomic.svg/25px-Nuvola_apps_katomic.svg.png" decoding="async" width="25" height="25" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/5/55/Nuvola_apps_katomic.svg/38px-Nuvola_apps_katomic.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/5/55/Nuvola_apps_katomic.svg/50px-Nuvola_apps_katomic.svg.png 2x" data-file-width="128" data-file-height="128" /></a></span> <b><a href="/wiki/Portale:Fisica" title="Portale:Fisica">Portale Fisica</a></b></div></div></div>    </div><noscript><img src="https://login.wikimedia.org/wiki/Special:CentralAutoLogin/start?type=1x1" alt="" width="1" height="1" style="border: none; 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