{"id":221,"date":"2014-11-27T19:11:42","date_gmt":"2014-11-27T19:11:42","guid":{"rendered":"http:\/\/fisicaevestibular.com.br\/novo\/?page_id=221"},"modified":"2024-08-20T10:21:25","modified_gmt":"2024-08-20T10:21:25","slug":"campo-eletrico","status":"publish","type":"page","link":"https:\/\/fisicaevestibular.com.br\/novo\/eletricidade\/eletrostatica\/campo-eletrico\/","title":{"rendered":"Campo El\u00e9trico"},"content":{"rendered":"

CAMPO EL\u00c9TRICO<\/b><\/span><\/span><\/span><\/p>\n

Observe a analogia entre os campos a seguir:<\/b><\/span><\/span><\/span> <\/b>A Terra<\/b><\/span><\/span><\/span> <\/b>origina no espa\u00e7o, ao seu redor<\/b><\/span><\/span><\/span>, um <\/b><\/span><\/span><\/span>campo<\/b><\/span><\/span><\/span> tal que <\/b><\/span><\/span><\/span>todo corpo a\u00ed colocado \u00e9 atra\u00eddo gravitacionalmente para a sua superf\u00edcie<\/b><\/span><\/span><\/span> com <\/b><\/span><\/span><\/span>acelera\u00e7\u00e3o gravitacional\u00a0\"\"<\/b><\/span><\/span><\/span>\u00a0seguindo uma <\/b><\/span><\/span><\/span>trajet\u00f3ria radial,<\/b><\/span><\/span><\/span> em <\/b><\/span><\/span><\/span>dire\u00e7\u00e3o<\/b><\/span><\/span><\/span> ao <\/b><\/span><\/span><\/span>seu centro.<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Um <\/b><\/span><\/span><\/span>im\u00e3 origina no espa\u00e7o,<\/b><\/span><\/span><\/span> ao <\/b><\/span><\/span><\/span>seu redor um campo magn\u00e9tico\"\"<\/b><\/span><\/span><\/span> que faz <\/b><\/span><\/span><\/span>surgirem for\u00e7as<\/b><\/span><\/span><\/span> sobre <\/b><\/span><\/span><\/span>peda\u00e7os de ferro atraindo-os em sua dire\u00e7\u00e3o.<\/b><\/span><\/span><\/span><\/b><\/p>\n

Uma <\/b><\/span><\/span><\/span>carga el\u00e9trica Q<\/b><\/span><\/span><\/span> origina no <\/b><\/span><\/span><\/span>espa\u00e7o ao seu redor um campo el\u00e9trico\"\"\u00a0<\/b><\/span><\/span><\/span>que faz<\/b><\/span><\/span><\/span> surgirem for\u00e7as sobre uma carga de prova q quando colocada no interior desse campo.<\/b><\/span><\/span><\/span><\/p>\n


\n<\/b><\/span><\/span><\/span>Vetor Campo El\u00e9trico<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Se voc\u00ea colocar em<\/b><\/span><\/span><\/span> P pequenas cargas de prova q<\/b><\/span><\/span><\/span>1<\/b><\/span><\/span><\/sub><\/span>, q<\/b><\/span><\/span><\/span>2\u00a0<\/b><\/span><\/span><\/sub><\/span>e q<\/b><\/span><\/span><\/span>3<\/b><\/span><\/span><\/sub><\/span>\u00a0verificar\u00e1 <\/b><\/span><\/span><\/span>que <\/b><\/span><\/span><\/span>sobre cada uma delas<\/b><\/span><\/span><\/span><\/p>\n

\"\"\"\"\"\"<\/p>\n

\"\"<\/p>\n

\"\"<\/p>\n

\u00a0<\/b><\/span><\/span><\/span><\/p>\n

Campo el\u00e9trico gerado por uma carga pontual Q<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

\"\"<\/p>\n

Observe <\/b><\/span><\/span><\/span>atentamente<\/b><\/span><\/span><\/span> as <\/b><\/span><\/span><\/span>figuras abaixo<\/b><\/span><\/span><\/span> onde a <\/b><\/span><\/span><\/span>carga geradora Q > 0<\/b><\/span><\/span><\/span> provoca em <\/b><\/span><\/span><\/span>q<\/b><\/span><\/span><\/span>1 <\/b><\/span><\/span><\/sub><\/span>< 0<\/b><\/span><\/span><\/span> <\/b>localizado<\/b><\/span><\/span><\/span> em <\/b><\/span><\/span><\/span>M<\/b><\/span><\/span><\/span> uma <\/b><\/span><\/span><\/span>for\u00e7a de atra\u00e7\u00e3o\u00a0\"\"<\/b><\/span><\/span><\/span>\u00a0e, como <\/b><\/span><\/span><\/span>q<\/b><\/span><\/span><\/span>1<\/b><\/span><\/span><\/sub><\/span>\u00a0\u00e9 positiva<\/b><\/span><\/span><\/span>, <\/b><\/span><\/span><\/span>campo e for\u00e7a<\/b><\/span><\/span><\/span>tem <\/b><\/span><\/span><\/span>mesma dire\u00e7\u00e3o e sentidos<\/b><\/span><\/span><\/span> <\/b>opostos<\/b><\/span><\/span><\/span>, estando \"\"<\/b><\/span><\/span><\/span>\u00a0em M se afastando de Q > 0.<\/b><\/span><\/span><\/span><\/p>\n

Verifique agora que a <\/b><\/span><\/span><\/span>carga geradora Q > 0<\/b><\/span><\/span><\/span> provoca em <\/b><\/span><\/span><\/span>q<\/b><\/span><\/span><\/span>2 <\/b><\/span><\/span><\/sub><\/span>> 0<\/b><\/span><\/span><\/span> localizado em <\/b><\/span><\/span><\/span>N uma for\u00e7a de
\nrepuls\u00e3o\u00a0\"\"<\/b><\/span><\/span><\/span>\u00a0e, como <\/b><\/span><\/span><\/span>q<\/b><\/span><\/span><\/span>2<\/b><\/span><\/span><\/sub><\/span>\u00a0\u00e9 positiva, campo e for\u00e7a t\u00eam mesma dire\u00e7\u00e3o e mesmo sentido, estando\u00a0\"\"<\/b><\/span><\/span><\/span>em <\/b><\/span><\/span><\/span>N se afastando de Q > 0.<\/b><\/span><\/span><\/span><\/b><\/p>\n

\"\"<\/p>\n

Generalizando<\/b><\/span><\/span><\/span>: em <\/b><\/span><\/span><\/span>qualquer ponto<\/b><\/span><\/span><\/span> do\u00a0campo gerado por Q > 0<\/b><\/span><\/span><\/span>\u00a0colocando-se <\/b><\/span><\/span><\/span>cargas de prova positivas ou negativas, o campo gerado\u00a0ser\u00e1 sempre de<\/b><\/span><\/span><\/span>afastamento.<\/b><\/span><\/span><\/span><\/p>\n

Analogamente,<\/b><\/span><\/span><\/span> se a\u00a0<\/b><\/span><\/span><\/span>carga geradora fosse negativa Q < 0,<\/b><\/span><\/span><\/span> em\u00a0<\/b><\/span><\/span><\/span>todos os pontos<\/b><\/span><\/span><\/span> o <\/b><\/span><\/span><\/span>campo el\u00e9trico gerado seria de <\/b><\/span><\/span><\/span>aproxima\u00e7\u00e3o.<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

\"\"<\/p>\n

\"\"<\/p>\n


\n<\/b><\/span><\/span><\/span>Campo el\u00e9trico gerado num ponto P por v\u00e1rias cargas puntiformes<\/b><\/span><\/span><\/span><\/p>\n

Num <\/b><\/span><\/span><\/span>dado ponto P <\/b><\/span><\/span><\/span>do espa\u00e7o o <\/b><\/span><\/span><\/span>vetor campo el\u00e9trico resultante<\/b><\/span><\/span><\/span>, devido \u00e0 <\/b><\/span><\/span><\/span>a\u00e7\u00e3o<\/b><\/span><\/span><\/span> de <\/b><\/span><\/span><\/span>v\u00e1rias cargas,<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

corresponde \u00e0 <\/b><\/span><\/span><\/span>soma vetorial\u00a0dos campos produzidos por cada uma dessas cargas individualmente.<\/b><\/span><\/span><\/span><\/p>\n


\n<\/b><\/span><\/span><\/span>Gr\u00e1ficos do campo el\u00e9trico em fun\u00e7\u00e3o de <\/b><\/span><\/span><\/span>Q <\/b><\/span><\/span><\/span>e de <\/b><\/span><\/span><\/span>d<\/b><\/span><\/span><\/span><\/p>\n

Observe na express\u00e3o <\/b><\/span><\/span><\/span>E = K.Q\/d<\/b><\/span><\/span><\/span>2<\/b><\/span><\/span><\/sup><\/span>\u00a0<\/b><\/span><\/span><\/sup><\/span>que a <\/b><\/span><\/span><\/span>intensidade de \"\" \u00e9 diretamente proporcional a <\/b><\/span><\/span><\/span>Q<\/b><\/span><\/span><\/span> e<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

inversamente proporcional ao quadrado de <\/b><\/span><\/span><\/span>d<\/b><\/span><\/span><\/span>,<\/b><\/span><\/span><\/span> cujos <\/b><\/span><\/span><\/span>gr\u00e1ficos <\/b><\/span><\/span><\/span>est\u00e3o representados nas <\/b><\/span><\/span><\/span>figuras.<\/b><\/span><\/span><\/span><\/p>\n

Campo el\u00e9trico uniforme<\/b><\/span><\/span><\/span><\/p>\n

Observa-se <\/b><\/span><\/span><\/span>experimentalmente <\/b><\/span><\/span><\/span>que, <\/b><\/span><\/span><\/span>entre duas placas condutoras eletrizadas com cargas de mesmo<\/b><\/span><\/span><\/span> <\/b>m\u00f3dulo,<\/b><\/span><\/span><\/span> mas de <\/b><\/span><\/span><\/span>sinais contr\u00e1rios<\/b><\/span><\/span><\/span> existe um <\/b><\/span><\/span><\/span>campo el\u00e9trico uniforme<\/b><\/span><\/span><\/span>, ou seja, o <\/b><\/span><\/span><\/span>vetor campo el\u00e9trico<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

possui em todos os seus infinitos pontos, mesma intensidade, mesma dire\u00e7\u00e3o e mesmo sentido.<\/b><\/span><\/span><\/span><\/p>\n

O que voc\u00ea deve saber, orienta\u00e7\u00f5es e dicas<\/b><\/span><\/span><\/span><\/p>\n

\"\" Rela\u00e7\u00e3o<\/b><\/span><\/span><\/span> entre <\/b><\/span><\/span><\/span>campo el\u00e9trico e for\u00e7a el\u00e9trica<\/b><\/span><\/span><\/span> sobre uma <\/b><\/span><\/span><\/span>carga de prova q<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

\"\" Caracter\u00edsticas <\/b><\/span><\/span><\/span>do <\/b><\/span><\/span><\/span>vetor campo el\u00e9trico<\/b><\/span><\/span><\/span> gerado pela <\/b><\/span><\/span><\/span>carga<\/b><\/span><\/span><\/span> <\/b>fonte Q num ponto P, distante d de Q.<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

\"\" Campo el\u00e9trico<\/b><\/span><\/span><\/span> originado por <\/b><\/span><\/span><\/span>v\u00e1rias cargas fontes<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

\"\" Gr\u00e1fico ExQ e Exd.<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

\"\" O <\/b><\/span><\/span><\/span>vetor campo el\u00e9trico<\/b><\/span><\/span><\/span> de todos os <\/b><\/span><\/span><\/span>infinitos pontos localizados entre duas placas eletrizadas<\/b><\/span><\/span><\/span> com <\/b><\/span><\/span><\/span>cargas de mesmo m\u00f3dulo e sinais contr\u00e1rios \u00e9 constante<\/b><\/span><\/span><\/span> (tem<\/b><\/span><\/span><\/span>sempre a mesma intensidade,<\/b><\/span><\/span><\/span><\/b><\/p>\n

\"\"<\/p>\n

mesma dire\u00e7\u00e3o e mesmo sentido<\/b><\/span><\/span><\/span>).<\/b><\/span><\/span><\/span><\/p>\n

Se <\/b><\/span><\/span><\/span>afasta da placa com cargas positivas e se aproxima da placa com cargas negativas.<\/b><\/span><\/span><\/span><\/p>\n

\"\" Quando se coloca um <\/b><\/span><\/span><\/span>isolante entre as cargas (placas),<\/b><\/span><\/span><\/span> mudam-se as <\/b><\/span><\/span><\/span>condi\u00e7\u00f5es do meio<\/b><\/span><\/span><\/span> entre as mesmas.<\/b><\/span><\/span><\/span><\/p>\n

Por isso a <\/b><\/span><\/span><\/span>lei de Coulomb para cargas puntiformes \u00e9:<\/b><\/span><\/span><\/span> E = (1\/4.\u03c0\u03b5).Q\/r<\/b><\/span><\/span><\/span>2<\/b><\/span><\/span><\/sup><\/span>.<\/b><\/span><\/span><\/span><\/p>\n

A <\/b><\/span><\/span><\/span>constante<\/b><\/span><\/span><\/span>\u00a0\u03b5\u00a0\u00e9 \u00e1 <\/b><\/span><\/span><\/span>permissividade el\u00e9trica do meio.<\/b><\/span><\/span><\/span><\/b><\/p>\n

Portanto, ao se <\/b><\/span><\/span><\/span>colocar um isolante entre as placas,<\/b><\/span><\/span><\/span> o <\/b><\/span><\/span><\/span>campo el\u00e9trico entre elas varia.<\/b><\/span><\/span><\/span> A <\/b><\/span><\/span><\/span>figura abaixo<\/b><\/span><\/span><\/span> ilustra um exemplo para <\/b><\/span><\/span><\/span>duas placas carregadas com cargas de sinais opostos.<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Confira os Exerc\u00edcios Propostos<\/b><\/span><\/a><\/h3>\n","protected":false},"excerpt":{"rendered":"

CAMPO EL\u00c9TRICO Observe a analogia entre os campos a seguir: A Terra origina no espa\u00e7o, ao seu redor, um campo tal que todo corpo a\u00ed colocado \u00e9 atra\u00eddo gravitacionalmente para a sua superf\u00edcie com acelera\u00e7\u00e3o gravitacional\u00a0\u00a0seguindo uma trajet\u00f3ria radial, em dire\u00e7\u00e3o ao seu centro. Um im\u00e3 origina no espa\u00e7o, ao seu redor um campo magn\u00e9tico que faz surgirem for\u00e7as sobre<\/p>\n","protected":false},"author":1,"featured_media":0,"parent":193,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"","meta":{"om_disable_all_campaigns":false,"_monsterinsights_skip_tracking":false,"_monsterinsights_sitenote_active":false,"_monsterinsights_sitenote_note":"","_monsterinsights_sitenote_category":0,"footnotes":""},"class_list":["post-221","page","type-page","status-publish","hentry"],"aioseo_notices":[],"_links":{"self":[{"href":"https:\/\/fisicaevestibular.com.br\/novo\/wp-json\/wp\/v2\/pages\/221","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/fisicaevestibular.com.br\/novo\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/fisicaevestibular.com.br\/novo\/wp-json\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/fisicaevestibular.com.br\/novo\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/fisicaevestibular.com.br\/novo\/wp-json\/wp\/v2\/comments?post=221"}],"version-history":[{"count":5,"href":"https:\/\/fisicaevestibular.com.br\/novo\/wp-json\/wp\/v2\/pages\/221\/revisions"}],"predecessor-version":[{"id":10588,"href":"https:\/\/fisicaevestibular.com.br\/novo\/wp-json\/wp\/v2\/pages\/221\/revisions\/10588"}],"up":[{"embeddable":true,"href":"https:\/\/fisicaevestibular.com.br\/novo\/wp-json\/wp\/v2\/pages\/193"}],"wp:attachment":[{"href":"https:\/\/fisicaevestibular.com.br\/novo\/wp-json\/wp\/v2\/media?parent=221"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}