{"id":1839,"date":"2016-01-25T00:48:32","date_gmt":"2016-01-25T00:48:32","guid":{"rendered":"http:\/\/fisicaevestibular.com.br\/novo\/?page_id=1839"},"modified":"2024-08-19T16:33:53","modified_gmt":"2024-08-19T16:33:53","slug":"receptores-associacao-de-geradores-com-receptores-lei-de-pouillet","status":"publish","type":"page","link":"https:\/\/fisicaevestibular.com.br\/novo\/eletricidade\/eletrodinamica\/receptores-associacao-de-geradores-com-receptores-lei-de-pouillet\/","title":{"rendered":"Lei de Pouillet – Receptores"},"content":{"rendered":"

Receptores \u2013 Associa\u00e7\u00e3o de geradores com receptores \u2013 Lei de Pouillet<\/b><\/span><\/span><\/span><\/p>\n

Receptor el\u00e9trico<\/b><\/span><\/span><\/span><\/p>\n

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

D<\/b><\/span><\/span><\/span>ispositivo<\/b><\/span><\/span><\/span> que <\/b><\/span><\/span><\/span>converte energia el\u00e9trica em outra forma de energia, n\u00e3o exclusivamente t\u00e9rmica. Exemplos:<\/b><\/span><\/span><\/span> <\/b>motores el\u00e9tricos, ventiladores, liquidificadores, geladeiras, aparelhos de sons, v\u00eddeos, celulares, computadores, etc.<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Um <\/b><\/span><\/span><\/span>ventilador, por exemplo<\/b><\/span><\/span><\/span>, <\/b><\/span><\/span><\/span>converte energia t\u00e9rmica em energia mec\u00e2nica;<\/b><\/span><\/span><\/span> essa <\/b><\/span><\/span><\/span>convers\u00e3o,<\/b><\/span><\/span><\/span> entretanto, <\/b><\/span><\/span><\/span>n\u00e3o \u00e9 integral,<\/b><\/span><\/span><\/span> pois uma <\/b><\/span><\/span><\/span>parte da energia\u00a0 converte-se, inevitavelmente, em energia t\u00e9rmica.<\/b><\/span><\/span><\/span><\/p>\n

Grandezas caracter\u00edsticas de um receptor el\u00e9trico<\/b><\/span><\/span><\/span><\/p>\n

S<\/b><\/span><\/span><\/span>\u00e3o duas:<\/b><\/span><\/span><\/span> a <\/b><\/span><\/span><\/span>primeira<\/b><\/span><\/span><\/span> \u00e9 a <\/b><\/span><\/span><\/span>for\u00e7a contra-eletromotriz (E\u2019),<\/b><\/span><\/span><\/span> grandeza (<\/b><\/span><\/span><\/span>medida<\/b><\/span><\/span><\/span> em <\/b><\/span><\/span><\/span>volts \u201c1V=1J\/C\u201d<\/b><\/span><\/span><\/span>) <\/b><\/span><\/span><\/span>definida <\/b><\/span><\/span><\/span>como a <\/b><\/span><\/span><\/span>raz\u00e3o entre o trabalho (W) e a quantidade de carga (Q) que efetua esse trabalho no<\/b><\/span><\/span><\/span> interior <\/b><\/span><\/span><\/span>do receptor e que \u00e9 a diferen\u00e7a de potencial realmente aproveitada para produzir a energia n\u00e3o t\u00e9rmica; a segunda \u00e9 sua resist\u00eancia interna r\u2019.<\/b><\/span><\/span><\/span><\/p>\n

Representa\u00e7\u00e3o esquem\u00e1tica de um receptor<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Circuito el\u00e9trico com um gerador alimentando um receptor<\/b><\/span><\/span><\/span><\/p>\n

\u00a0No <\/b><\/span><\/span><\/span>circuito da figura, um gerador (bateria)<\/b><\/span><\/span><\/span> <\/b>alimenta um receptor (motor),<\/b><\/span><\/span><\/span> estabelecendo nele uma <\/b><\/span><\/span><\/span>diferen\u00e7a de potencial.<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Equa\u00e7\u00e3o do receptor<\/b><\/span><\/span><\/span><\/p>\n

Considere um <\/b><\/span><\/span><\/span>receptor el\u00e9trico<\/b><\/span><\/span><\/span> (ventiladorzinho el\u00e9trico, por exemplo), recebendo <\/b><\/span><\/span><\/span>U =2 V de uma<\/b><\/span><\/span><\/span> <\/b>pilha <\/b><\/span><\/span><\/span>(significa que o motor recebe da pilha 2J de energia el\u00e9trica para cada 1C de carga que passa por ele).<\/b><\/span><\/span><\/span><\/p>\n

Suponha que U\u2019 = r\u2019.i = 0,5V<\/b><\/span><\/span><\/span> (significa que uma parcela de energia el\u00e9trica igual a 0,5J recebida pelo ventilador, para cada 1C de carga que passa por ele, \u00e9<\/b><\/span><\/span><\/span>convertida em energia t\u00e9rmica<\/b><\/span><\/span><\/span>, <\/b><\/span><\/span><\/span>aquecendo inutilmente o motor (energia dissipada, perdida, desperdi\u00e7ada).<\/b><\/span><\/span><\/span><\/p>\n

Para o <\/b><\/span><\/span><\/span>motor (receptor) produzir energia mec\u00e2nica<\/b><\/span><\/span><\/span>, <\/b><\/span><\/span><\/span>resta\u00a0<\/b><\/span><\/span><\/span> \"\"\u00a0 <\/b><\/span><\/span><\/span>E\u2019 =U \u2013 r\u2019.i =<\/b><\/span><\/span><\/span>2 \u2013 0,5\u00a0\"\" <\/b><\/span><\/span><\/span>E\u2019 = 1,5V, o que significa<\/b><\/span><\/span><\/span> que uma <\/b><\/span><\/span><\/span>energia el\u00e9trica de 1,5J \u00e9 convertida utilmente em energia n\u00e3o t\u00e9rmica (mec\u00e2nica, no caso), para cada 1C de carga que passa pelo motor (receptor).<\/b><\/span><\/span><\/span><\/p>\n

Assim:<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Curva caracter\u00edstica do receptor<\/b><\/span><\/span><\/span><\/p>\n

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

Pot\u00eancias de um receptor (equa\u00e7\u00f5es)<\/b><\/span><\/span><\/span><\/p>\n

\"\"\u00a0 <\/span>Pot\u00eancia total (P<\/b><\/span><\/span><\/span>t<\/b><\/span><\/span><\/sub><\/span>)<\/b><\/span><\/span><\/span> \"\" <\/b><\/span><\/span><\/span>corresponde \u00e0 energia total recebida pelo receptor da fonte externa (gerador) por unidade de tempo:<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

\u00a0\"\" <\/span>Pot\u00eancia dissipada (P<\/b><\/span><\/span><\/span>d<\/b><\/span><\/span><\/sub><\/span>)<\/b><\/span><\/span><\/span> \"\" refere-se \u00e0 <\/b><\/span><\/span><\/span>pot\u00eancia consumida <\/b><\/span><\/span><\/span>(\u201cperdida\u201d, dissipada, sob forma t\u00e9rmica) pela <\/b><\/span><\/span><\/span>resist\u00eancia interna r\u2019<\/b><\/span><\/span><\/span> do receptor e fornecida por:<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

\"\"\u00a0<\/span>Pot\u00eancia \u00fatil (P<\/b><\/span><\/span><\/span>u<\/b><\/span><\/span><\/sub><\/span>)<\/b><\/span><\/span><\/span> \"\" <\/b><\/span><\/span><\/span>pot\u00eancia aproveitada pelo receptor<\/b><\/span><\/span><\/span> para seu <\/b><\/span><\/span><\/span>funcionamento normal,<\/b><\/span><\/span><\/span> sob <\/b><\/span><\/span><\/span>forma n\u00e3o t\u00e9rmica<\/b><\/span><\/span><\/span>.<\/b><\/span><\/span><\/span><\/p>\n

Exemplo:<\/b><\/span><\/span><\/span> num <\/b><\/span><\/span><\/span>ventilador \u00e9 a parcela da energia total que \u00e9 transformada em energia exclusivamente mec\u00e2nica, para girar as p\u00e1s do mesmo.<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Rendimento (\u03b7) de um receptor<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/span><\/p>\n

\u00a0O <\/b><\/span><\/span><\/span>rendimento (\u03b7) de um receptor \u00e9 de<\/b><\/span><\/span><\/span>finido<\/b><\/span><\/span><\/span> como sendo <\/b><\/span><\/span><\/span>a raz\u00e3o entre sua pot\u00eancia \u00fatil (P<\/b><\/span><\/span><\/span>u<\/b><\/span><\/span><\/sub><\/span>) e sua pot\u00eancia total P<\/b><\/span><\/span><\/span>t<\/b><\/span><\/span><\/sub><\/span>):<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

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

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

\"\"<\/p>\n

\"\"<\/p>\n

\"\"<\/p>\n

\"\"<\/p>\n

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

\"\"<\/p>\n

\"\"<\/p>\n

\u00a0<\/span>Se voc\u00ea <\/b><\/span><\/span><\/span>paralisar o eixo de um motor el\u00e9trico,<\/b><\/span><\/span><\/span> ele funcionar\u00e1 como um <\/b><\/span><\/span><\/span>resistor, com toda sua energia el\u00e9trica se transformando em energia t\u00e9rmica, podendo queim\u00e1-lo.<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

\u00a0<\/span>A <\/b><\/span><\/span><\/span>pot\u00eancia el\u00e9trica que o gerador entrega ao receptor \u00e9 a pot\u00eancia \u00fatil<\/b><\/span><\/span><\/span> <\/b>do gerador (U.i).<\/b><\/span><\/span><\/span><\/b><\/p>\n

Para o <\/b><\/span><\/span><\/span>receptor, essa mesma pot\u00eancia representa a pot\u00eancia total.<\/b><\/span><\/span><\/span> Desse total, uma <\/b><\/span><\/span><\/span>parcela \u00e9 \u00fatil (E\u2019.i) e a outra dissipada (r\u2019.i<\/b><\/span><\/span><\/span>2<\/b><\/span><\/span><\/sup><\/span>). <\/b><\/span><\/span><\/span>Observe atentamente o esquema abaixo.<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

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

Lei de Pouillet<\/b><\/span><\/span><\/span> – <\/b><\/span><\/span><\/span>Circuito el\u00e9trico de malha \u00fanica com geradores e receptores<\/b><\/span><\/span><\/span><\/p>\n

Seja um <\/b><\/span><\/span><\/span>gerador de for\u00e7a eletromotriz (fem) e resist\u00eancia interna r, um receptor de for\u00e7a contra- eletromotriz (fcem) E\u2019 e resist\u00eancia interna r\u2019 e um resistor de resist\u00eancia R, associados em s\u00e9rie<\/b><\/span><\/span><\/span> <\/b>conforme a figura,<\/b><\/span><\/span><\/span> constituindo um <\/b><\/span><\/span><\/span>circuito el\u00e9trico de malha \u00fanica.<\/b><\/span><\/span><\/span><\/b><\/p>\n

Como est\u00e3o em <\/b><\/span><\/span><\/span>s\u00e9rie a intensidade da corrente el\u00e9trica i \u00e9 a mesma em cada dispositivo.<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

O <\/b><\/span><\/span><\/span>gerador origina em seus terminais A e B uma ddp (tens\u00e3o) U <\/b><\/span><\/span><\/span>que provoca uma <\/b><\/span><\/span><\/span>eleva\u00e7\u00e3o de<\/b><\/span><\/span><\/span> <\/b>potencial e que deve ser igual \u00e0 soma das quedas de potenciais provocadas pelo resistor U\u2019 e pelo<\/b><\/span><\/span><\/span> <\/b>receptor U\u2019\u2019, ou seja, U = U\u2019 + U\u2019\u2019<\/b><\/span><\/span><\/span>\u00a0 \"\"\u00a0 <\/b><\/span><\/span><\/span>U = E \u2013 r.i\u00a0 \"\"\u00a0 U\u2019 = R.i\u00a0 \"\"\u00a0 U\u2019 = E\u2019 + r\u2019.i<\/b><\/span><\/span><\/span>\u00a0 \"\"\u00a0 E – r.i = R.i + E\u2019 + r\u2019.i\u00a0 \"\"\u00a0 E \u2013 E\u2019=(r + r\u2019 + R).i\u00a0\"\"\u00a0 i=(E \u2013 E\u2019)\/(r + r\u2019 + R)\u00a0 \"\"\u00a0 generalizando\u00a0 \"\"\u00a0 em circuitos de uma \u00fanica malha:<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Analise com <\/b><\/span><\/span><\/span>aten\u00e7\u00e3o esse exemplo:<\/b><\/span><\/span><\/span> No <\/b><\/span><\/span><\/span>circuito esquematizado abaixo, determine:<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

a)<\/b><\/span><\/span><\/span> a <\/b><\/span><\/span><\/span>intensidade da corrente el\u00e9trica no gerador, no receptor e na resist\u00eancia de 5\u2126.<\/b><\/span><\/span><\/span><\/p>\n

b)<\/b><\/span><\/span><\/span> A <\/b><\/span><\/span><\/span>diferen\u00e7a de potencial nos terminais do gerador, do receptor e do resistor de 5\u2126.<\/b><\/span><\/span><\/span><\/p>\n

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

a)<\/b><\/span><\/span><\/span> Como o <\/b><\/span><\/span><\/span>sentido da corrente el\u00e9trica n\u00e3o \u00e9 especificado,<\/b><\/span><\/span><\/span> ela <\/b><\/span><\/span><\/span>obedece ao de maior fem, que \u00e9 a do<\/b><\/span><\/span><\/span> <\/b>gerador,<\/b><\/span><\/span><\/span> onde a <\/b><\/span><\/span><\/span>corrente sai pelo p\u00f3lo positivo.<\/b><\/span><\/span><\/span><\/b><\/p>\n

No caso, o de <\/b><\/span><\/span><\/span>fem 17V \u00e9 o gerador<\/b><\/span><\/span><\/span> e a <\/b><\/span><\/span><\/span>corrente no circuito \u00e9 no sentido anti-hor\u00e1rio,<\/b><\/span><\/span><\/span> pois a <\/b><\/span><\/span><\/span>corrente<\/b><\/span><\/span><\/span> <\/b>sai do p\u00f3lo positivo do mesmo.<\/b><\/span><\/span><\/span> Deve-se <\/b><\/span><\/span><\/span>transformar o circuito num de malha \u00fanica e, assim, deve-se resolver a associa\u00e7\u00e3o paralelo (8\/2 = 4\u2126).<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Aplicando a <\/b><\/span><\/span><\/span>lei de Pouillet<\/b><\/span><\/span><\/span>\u00a0\"\" \u00a0 <\/b><\/span><\/span><\/span>i = (\u2211E – \u2211E\u2019)\/\u2211R<\/b><\/span><\/span><\/span> = (17 \u2013 10)\/(4 + 2 + 1 + 5 + 2)\u00a0 \"\"\u00a0 i = 7\/14\u00a0 \"\"\u00a0<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/span>i =<\/b><\/span><\/span><\/span> <\/b>0,5A<\/b><\/span><\/span><\/span>, que \u00e9 a <\/b><\/span><\/span><\/span>mesma atrav\u00e9s de todos os elementos do circuito, pois est\u00e3o em s\u00e9rie.<\/b><\/span><\/span><\/span><\/p>\n

b)<\/b><\/span><\/span><\/span> <\/b>Gerador<\/b><\/span><\/span><\/span>\u00a0 \"\"\u00a0 <\/b><\/span><\/span><\/span>U<\/b><\/span><\/span><\/span>g <\/b><\/span><\/span><\/sub><\/span>= E \u2013 r.i<\/b><\/span><\/span><\/span> = 17 \u2013 2.0,5\u00a0 \"\"\u00a0\u00a0<\/b><\/span><\/span><\/span>U<\/b><\/span><\/span><\/span>g <\/b><\/span><\/span><\/sub><\/span>= 16V<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/span>\u00a0\"\"\u00a0 <\/b><\/span><\/span><\/span>receptor<\/b><\/span><\/span><\/span>\u00a0 \"\"\u00a0 <\/b><\/span><\/span><\/span>U<\/b><\/span><\/span><\/span>r <\/b><\/span><\/span><\/sub><\/span>= E\u2019 + r\u2019.i<\/b><\/span><\/span><\/span> = 10 + 1.0,5\u00a0 \"\"\u00a0<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/span>U<\/b><\/span><\/span><\/span>r <\/b><\/span><\/span><\/sub><\/span>= 9,5V<\/b><\/span><\/span><\/span>\u00a0 \"\"\u00a0 <\/b><\/span><\/span><\/span>U<\/b><\/span><\/span><\/span>5\u2126 <\/b><\/span><\/span><\/sub><\/span>= R.i <\/b><\/span><\/span><\/span>= 5.0,5\u00a0 \"\"\u00a0\u00a0<\/b><\/span><\/span><\/span>U<\/b><\/span><\/span><\/span>5\u2126 <\/b><\/span><\/span><\/sub><\/span>= 2,5V.<\/b><\/span><\/span><\/span><\/p>\n

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

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

\"\"<\/p>\n

\"\"<\/p>\n

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

\"\"<\/p>\n

\"\"<\/p>\n

\"\"<\/p>\n

 <\/p>\n

Confira os exerc\u00edcios com resolu\u00e7\u00e3o comentada<\/span><\/a><\/h3>\n","protected":false},"excerpt":{"rendered":"

Receptores \u2013 Associa\u00e7\u00e3o de geradores com receptores \u2013 Lei de Pouillet Receptor el\u00e9trico \u00a0 Dispositivo que converte energia el\u00e9trica em outra forma de energia, n\u00e3o exclusivamente t\u00e9rmica. Exemplos: motores el\u00e9tricos, ventiladores, liquidificadores, geladeiras, aparelhos de sons, v\u00eddeos, celulares, computadores, etc. Um ventilador, por exemplo, converte energia t\u00e9rmica em energia mec\u00e2nica; essa convers\u00e3o, entretanto, n\u00e3o \u00e9 integral, pois uma parte da<\/p>\n","protected":false},"author":1,"featured_media":0,"parent":1676,"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-1839","page","type-page","status-publish","hentry"],"aioseo_notices":[],"_links":{"self":[{"href":"https:\/\/fisicaevestibular.com.br\/novo\/wp-json\/wp\/v2\/pages\/1839","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=1839"}],"version-history":[{"count":4,"href":"https:\/\/fisicaevestibular.com.br\/novo\/wp-json\/wp\/v2\/pages\/1839\/revisions"}],"predecessor-version":[{"id":10545,"href":"https:\/\/fisicaevestibular.com.br\/novo\/wp-json\/wp\/v2\/pages\/1839\/revisions\/10545"}],"up":[{"embeddable":true,"href":"https:\/\/fisicaevestibular.com.br\/novo\/wp-json\/wp\/v2\/pages\/1676"}],"wp:attachment":[{"href":"https:\/\/fisicaevestibular.com.br\/novo\/wp-json\/wp\/v2\/media?parent=1839"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}