{"id":1833,"date":"2016-01-25T00:42:49","date_gmt":"2016-01-25T00:42:49","guid":{"rendered":"http:\/\/fisicaevestibular.com.br\/novo\/?page_id=1833"},"modified":"2024-11-07T12:59:45","modified_gmt":"2024-11-07T12:59:45","slug":"resolucao-comentada-de-circuitos-com-geradores","status":"publish","type":"page","link":"https:\/\/fisicaevestibular.com.br\/novo\/eletricidade\/eletrodinamica\/resolucao-comentada-de-circuitos-com-geradores\/","title":{"rendered":"Circuitos com geradores – Resolu\u00e7\u00e3o"},"content":{"rendered":"

Resolu\u00e7\u00e3o comentada de Circuitos com geradores<\/b><\/span><\/span><\/span><\/p>\n

A <\/b><\/span><\/span><\/span>resolu\u00e7\u00e3o<\/b><\/span><\/span><\/span> desse tipo de associa\u00e7\u00f5es \u00e9 feita por <\/b><\/span><\/span><\/span>etapas at\u00e9 chegar ao resistor equivalente e depois ir retornando e achando o que \u00e9 pedido.<\/b><\/span><\/span><\/span><\/p>\n

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

01-(UNESP-SP)<\/b><\/span><\/span><\/span> <\/b>Dois resistores, um de 20\u2126 e outro de resist\u00eancia R desconhecida, est\u00e3o ligados em s\u00e9rie a uma bateria de 6,0V e resist\u00eancia interna desprez\u00edvel, como mostra a figura.<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Se a corrente no circuito \u00e9 0,1 A, o valor da resist\u00eancia R, em ohms, \u00e9:<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

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

02-(FUVEST-SP)<\/b><\/span><\/span><\/span> No circuito as l\u00e2mpadas L<\/b><\/span><\/span><\/span>1<\/b><\/span><\/span><\/sub><\/span>, L<\/b><\/span><\/span><\/span>2<\/b><\/span><\/span><\/sub><\/span>\u00a0e L<\/b><\/span><\/span><\/span>3<\/b><\/span><\/span><\/sub><\/span>\u00a0s\u00e3o id\u00eanticas com resistores de 30 ohms cada. A for\u00e7a eletromotriz vale 18V e C \u00e9 uma chave que est\u00e1 inicialmente fechada..<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

a) Qual a corrente que passa por L<\/b><\/span><\/span><\/span>2<\/b><\/span><\/span><\/sub><\/span>?<\/b><\/span><\/span><\/span><\/p>\n

b) Abrindo-se a chave C, o que acontece com o brilho da l\u00e2mpada L<\/b><\/span><\/span><\/span>1<\/b><\/span><\/span><\/sub><\/span>? Justifique.<\/b><\/span><\/span><\/span><\/p>\n

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

03-(FUVEST-SP)<\/b><\/span><\/span><\/span> No circuito representado na figura, G \u00e9 um gerador de for\u00e7a eletromotriz igual a 12 volts e resist\u00eancia interna desprez\u00edvel.<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Calcule a diferen\u00e7a de potencial, em volts, entre A e B, quando:<\/b><\/span><\/span><\/span><\/p>\n

a) a chave C est\u00e1 aberta<\/b><\/span><\/span><\/span><\/p>\n

b) a chave C est\u00e1 fechada<\/b><\/span><\/span><\/span><\/p>\n

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

04-(UNESP-SP)<\/b><\/span><\/span><\/span> Na figura, temos um circuito onde R<\/b><\/span><\/span><\/span>1<\/b><\/span><\/span><\/sub><\/span>\u00a0e R<\/b><\/span><\/span><\/span>2<\/b><\/span><\/span><\/sub><\/span>\u00a0s\u00e3o resistores fixos e R<\/b><\/span><\/span><\/span>3<\/b><\/span><\/span><\/sub><\/span>\u00a0\u00e9 um resistor vari\u00e1vel (reostato). A for\u00e7a eletromotriz \u00e9 de 1,2V. Os valores de R<\/b><\/span><\/span><\/span>1<\/b><\/span><\/span><\/sub><\/span>\u00a0e R<\/b><\/span><\/span><\/span>2<\/b><\/span><\/span><\/sub><\/span>\u00a0s\u00e3o,<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

\u00a0respectivamente, 2,0\u2126 e 3,0\u2126, enquanto que R<\/b><\/span><\/span><\/span>3<\/b><\/span><\/span><\/sub><\/span>\u00a0pode variar de 0,0\u2126 a 6,0\u2126. Entre que valores a diferen\u00e7a de potencial entre A e B pode variar? Justifique.<\/b><\/span><\/span><\/span><\/p>\n

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

05-(UFSCAR-SP)<\/b><\/span><\/span><\/span> No circuito da figura, os potenciais nos pontos A e C valem, respectivamente:<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

a) 2V e -1V\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/b><\/span><\/span><\/span><\/p>\n

b) 4V e 6V\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/b><\/span><\/span><\/span><\/p>\n

c) 12V e -8V\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/b><\/span><\/span><\/span><\/p>\n

d) 8V e -4V\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/b><\/span><\/span><\/span><\/p>\n

e) 16V e -16V<\/b><\/span><\/span><\/span><\/p>\n

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

06-(UFRJ-RJ<\/b><\/span><\/span><\/span>) No circuito da figura, o gerador tem for\u00e7a eletromotriz 12V e resist\u00eancia interna desprez\u00edvel. Liga-se o ponto A a terra. O potencial do terminal negativo do gerador \u00e9:<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

\"\"<\/p>\n

07-(FUVEST-SP)<\/b><\/span><\/span><\/span> O esquema mostra tr\u00eas fios ligados a uma fonte, entre os quais se ligam algumas l\u00e2mpadas iguais:<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

a) Qual a tens\u00e3o aplicada \u00e0s l\u00e2mpadas quando o fio neutro est\u00e1 ligado?<\/b><\/span><\/span><\/span><\/p>\n

b) Se o fio neutro quebrar no ponto P, qual a tens\u00e3o que ser\u00e1 aplicada \u00e0s duas l\u00e2mpadas de baixo?<\/b><\/span><\/span><\/span><\/p>\n

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

08-(UFMA)<\/b><\/span><\/span><\/span> A figura representa um circuito el\u00e9trico formado por uma associa\u00e7\u00e3o de resistores, alimentados atrav\u00e9s de uma bateria de 12V e resist\u00eancia interna 0,1\u2126.<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Determine a pot\u00eancia dissipada pelo resistor de 9\u2126<\/b><\/span><\/span><\/span><\/p>\n

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

09-(UFF-RJ)<\/b><\/span><\/span><\/span> Uma bateria B, de for\u00e7a eletromotriz\u00a0\u03b5=12V e resist\u00eancia interna r desconhecida, \u00e9 conectada a um circuito el\u00e9trico que cont\u00e9m um resistor de resist\u00eancia R=3,5\u2126 e uma chave S.<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Com o resistor imerso em 240g de \u00e1gua, a chave S \u00e9 ligada, permitindo que o circuito seja atravessado por uma corrente el\u00e9trica de intensidade igual a 3,0 A.\u00a0 considerando que n\u00e3o h\u00e1 dissipa\u00e7\u00e3o de energia\u00a0 nos fios de liga\u00e7\u00e3o e que a energia liberada no resistor \u00e9 utilizada integralmente para aquecer a \u00e1gua, determine: (calor espec\u00edfico da \u00e1gua c=1cal\/g<\/b><\/span><\/span><\/span>o<\/b><\/span><\/span><\/sup><\/span>C;1,0J=0,24cal).<\/b><\/span><\/span><\/span><\/p>\n

a) a resist\u00eancia interna da bateria<\/b><\/span><\/span><\/span><\/p>\n

b) a ddp nos terminais da bateria<\/b><\/span><\/span><\/span><\/p>\n

c) a pot\u00eancia \u00fatil e a efici\u00eancia do gerador<\/b><\/span><\/span><\/span><\/p>\n

d) a energia absorvida pela \u00e1gua durante os 10 minutos que sucedem a liga\u00e7\u00e3o de S.<\/b><\/span><\/span><\/span><\/p>\n

e) a varia\u00e7\u00e3o de temperatura da \u00e1gua 10 minutos ap\u00f3s S ser ligada<\/b><\/span><\/span><\/span><\/p>\n

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

10-(UFPE-PE)<\/b><\/span><\/span><\/span> No circuito a seguir qual o valor da for\u00e7a eletromotriz\u00a0\u03b5, em volts, se a corrente<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

fornecida pela bateria for igual a\u00a09,0 A? Considere desprez\u00edvel a resist\u00eancia interna da bateria.<\/b><\/span><\/span><\/span><\/p>\n

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

11- (Mackenzie-SP)<\/b><\/span><\/span><\/span> Tr\u00eas pequenas l\u00e2mpadas id\u00eanticas, cada uma com a inscri\u00e7\u00e3o nominal (0,5W – 1,0V), s\u00e3o ligadas em s\u00e9rie, conforme o circuito a seguir. Com a chave aberta, \u00a0a corrente que passa pelas l\u00e2mpadas tem intensidade de 300mA<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

. Com a chave fechada, a nova intensidade de corrente pelas l\u00e2mpadas ser\u00e1:<\/b><\/span><\/span><\/span><\/p>\n

a)187,5mA\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/b><\/span><\/span><\/span><\/p>\n

b) 375mA\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/b><\/span><\/span><\/span><\/p>\n

c) 400mA\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/b><\/span><\/span><\/span><\/p>\n

d) 525mA\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/b><\/span><\/span><\/span><\/p>\n

e) 700mA<\/b><\/span><\/span><\/span><\/p>\n

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

12- (Mackenzie-SP)<\/b><\/span><\/span><\/span> Quando a intensidade de corrente el\u00e9trica que passa no gerador do circuito el\u00e9trico a seguir \u00e9 2,0A, o rendimento do mesmo \u00e9 de 80%. A resist\u00eancia interna desse gerador vale:<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

\"\"<\/p>\n

13-(ITA-SP)<\/b><\/span><\/span><\/span> No circuito representado na figura, t\u00eam-se duas l\u00e2mpadas incandescentes id\u00eanticas, L<\/b><\/span><\/span><\/span>1<\/b><\/span><\/span><\/sub><\/span>\u00a0e L<\/b><\/span><\/span><\/span>2<\/b><\/span><\/span><\/sub><\/span>\u00a0, e tr\u00eas fontes id\u00eanticas, de mesma tens\u00e3o V. Ent\u00e3o, quando a chave \u00e9 fechada,<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

a) apagam-se as duas l\u00e2mpadas.\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/b><\/span><\/span><\/span><\/p>\n

b) o brilho da L<\/b><\/span><\/span><\/span>1<\/b><\/span><\/span><\/sub><\/span>\u00a0aumenta e o da L<\/b><\/span><\/span><\/span>2<\/b><\/span><\/span><\/sub><\/span>\u00a0permanece o mesmo.\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/b><\/span><\/span><\/span><\/p>\n

c) o brilho da L<\/b><\/span><\/span><\/span>2<\/b><\/span><\/span><\/sub><\/span>\u00a0aumenta e o da L<\/b><\/span><\/span><\/span>1<\/b><\/span><\/span><\/sub><\/span>\u00a0permanece o mesmo.<\/b><\/span><\/span><\/span><\/p>\n

d) o brilho das duas l\u00e2mpadas aumenta.\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/b><\/span><\/span><\/span><\/p>\n

e) o brilho das duas l\u00e2mpadas permanece o mesmo.<\/b><\/span><\/span><\/span><\/p>\n

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

14-(UERJ-RJ)<\/b><\/span><\/span><\/span> Uma lanterna funciona com duas pilhas iguais de 1,5 V ligadas em s\u00e9rie e uma l\u00e2mpada que consome 0,6 W quando submetida a uma tens\u00e3o de 3 V. Ao ligarmos a lanterna,<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

\u00a0a tens\u00e3o aplicada sobre a l\u00e2mpada vale 2,5 V.<\/b><\/span><\/span><\/span><\/p>\n

A resist\u00eancia interna, em ohms, de cada pilha, tem o valor de:<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

15-(UFRS-RS)<\/b><\/span><\/span><\/span> O circuito a seguir representa tr\u00eas pilhas ideais de 1, 5 V cada uma, um resistor R de resist\u00eancia el\u00e9trica 1, 0 \u2126 e um motor, todos ligados em s\u00e9rie.<\/b><\/span><\/span><\/span><\/p>\n

(Considere desprez\u00edvel a resist\u00eancia el\u00e9trica dos fios de liga\u00e7\u00e3o do circuito.)<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

A tens\u00e3o entre os terminais A e B do motor \u00e9 4, 0 V. Qual \u00e9 a pot\u00eancia el\u00e9trica consumida pelo motor?<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

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

16- (FGV-SP)<\/b><\/span><\/span><\/span> Capaz de cozer salsichas em apenas 20s, este eletrodom\u00e9stico \u00e9 um verdadeiro eletrocutador. Como uma salsicha tem em m\u00e9dia resist\u00eancia el\u00e9trica de 440KW. a passagem da corrente el\u00e9trica atrav\u00e9s dela envolve dissipa\u00e7\u00e3o de calor, cozinhando-a.<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

A energia empregada para preparar 6 salsichas \u00e9, em J, aproximadamente<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

17-(FUVEST-SP)<\/b><\/span><\/span><\/span> Uma jovem, para aquecer uma certa quantidade de massa M de \u00e1gua, utiliza, inicialmente, um filamento enrolado, cuja resist\u00eancia el\u00e9trica Ro \u00e9 igual a 12 \u2126, ligado a uma fonte de 120 V (situa\u00e7\u00e3o I).<\/b><\/span><\/span><\/span><\/p>\n

Desejando aquecer a \u00e1gua em dois recipientes, coloca, em cada um, metade da massa total de \u00e1gua (M\/2), para que sejam aquecidos por resist\u00eancias R<\/b><\/span><\/span><\/span>1<\/b><\/span><\/span><\/sub><\/span>\u00a0e R<\/b><\/span><\/span><\/span>2<\/b><\/span><\/span><\/sub><\/span>, ligadas \u00e0 mesma fonte (situa\u00e7\u00e3o II). A jovem obt\u00e9m essas duas resist\u00eancias, cortando o filamento inicial em partes n\u00e3o iguais, pois deseja que R<\/b><\/span><\/span><\/span>1<\/b><\/span><\/span><\/sub><\/span>\u00a0aque\u00e7a a \u00e1gua com duas vezes mais pot\u00eancia queR<\/b><\/span><\/span><\/span>2<\/b><\/span><\/span><\/sub><\/span>. Para analisar essas situa\u00e7\u00f5es:<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

a) Estime a pot\u00eancia P<\/b><\/span><\/span><\/span>o<\/b><\/span><\/span><\/sub><\/span>, em watts, que \u00e9 fornecida \u00e0 massa total de \u00e1gua, na situa\u00e7\u00e3o I.<\/b><\/span><\/span><\/span><\/p>\n

b) Determine os valores de R<\/b><\/span><\/span><\/span>1<\/b><\/span><\/span><\/sub><\/span>\u00a0e R<\/b><\/span><\/span><\/span>2<\/b><\/span><\/span><\/sub><\/span>, em ohms, para que no recipiente onde est\u00e1 R<\/b><\/span><\/span><\/span>1<\/b><\/span><\/span><\/sub><\/span>\u00a0a \u00e1gua receba duas vezes mais pot\u00eancia do que no recipiente onde est\u00e1 R<\/b><\/span><\/span><\/span>2<\/b><\/span><\/span><\/sub><\/span>, na situa\u00e7\u00e3o II.<\/b><\/span><\/span><\/span><\/p>\n

c) Estime a raz\u00e3o P\/P<\/b><\/span><\/span><\/span>o<\/b><\/span><\/span><\/sub><\/span>, que expressa quantas vezes mais pot\u00eancia \u00e9 fornecida na situa\u00e7\u00e3o II (P), ao conjunto dos dois recipientes, em rela\u00e7\u00e3o \u00e0 situa\u00e7\u00e3o I (P<\/b><\/span><\/span><\/span>o<\/b><\/span><\/span><\/sub><\/span>).<\/b><\/span><\/span><\/span><\/p>\n

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

18-(UFLA-MG)<\/b><\/span><\/span><\/span> No circuito el\u00e9trico abaixo E \u00e9 uma fonte de tens\u00e3o cont\u00ednua vari\u00e1vel. Pede-se:<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

a) A tens\u00e3o fornecida pela fonte de tens\u00e3o cont\u00ednua vari\u00e1vel E, de forma que a tens\u00e3o entre os pontos X e Y seja de 16V.<\/b><\/span><\/span><\/span><\/p>\n

b) Ajustando-se a fonte E para 240V, qual ser\u00e1 a tens\u00e3o entre os pontos X e Y?<\/b><\/span><\/span><\/span><\/p>\n

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

19-(MACKENZIE-SP)<\/b><\/span><\/span><\/span> Quando as l\u00e2mpadas L<\/b><\/span><\/span><\/span>1<\/b><\/span><\/span><\/sub><\/span>, L<\/b><\/span><\/span><\/span>2<\/b><\/span><\/span><\/sub><\/span>\u00a0e L<\/b><\/span><\/span><\/span>3<\/b><\/span><\/span><\/sub><\/span>\u00a0est\u00e3o ligadas ao gerador de f.e.m.\u03b5, conforme mostra a figura ao lado, dissipam, respectivamente, as pot\u00eancias 1,00 W, 2,00 W e 2,00 W, por efeito Joule.<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Nessas condi\u00e7\u00f5es, se a corrente na l\u00e2mpada l<\/b><\/span><\/span><\/span>3<\/b><\/span><\/span><\/sub><\/span>\u00a0\u00e9 de\u00a0 500 mA, a for\u00e7a eletromotriz do gerador \u00e9 de:<\/b><\/span><\/span><\/span><\/p>\n

a) 2,25 V\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 \u00a0\u00a0\u00a0\u00a0\u00a0<\/b><\/span><\/span><\/span><\/p>\n

b) 3,50 V\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/b><\/span><\/span><\/span><\/p>\n

c) 3,75 V\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/b><\/span><\/span><\/span><\/p>\n

d) 4,00 V\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/b><\/span><\/span><\/span><\/p>\n

e) 4,25 V<\/b><\/span><\/span><\/span><\/p>\n

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

20-(MACKENZIE-SP)<\/b><\/span><\/span><\/span> No laborat\u00f3rio de F\u00edsica, um aluno observou que ao fechar a chave ch do circuito a seguir, o valor da tens\u00e3o nos terminais do gerador passa a ser 3 vezes menor. Analisando esse fato, o aluno determinou que a resist\u00eancia interna do gerador vale:<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

a) 4 \u2126\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/b><\/span><\/span><\/span><\/p>\n

b) 6 \u2126\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/b><\/span><\/span><\/span><\/p>\n

c) 8 \u2126\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/b><\/span><\/span><\/span><\/p>\n

d) 10 \u2126\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/b><\/span><\/span><\/span><\/p>\n

e) 12 \u2126<\/b><\/span><\/span><\/span><\/p>\n

21-(UFRJ-RJ)<\/b><\/span><\/span><\/span> Uma bateria ideal de for\u00e7a eletromotriz\u00a0\u03b5\u00a0est\u00e1 ligada a um circuito como ilustra a figura a seguir.<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Calcule a diferen\u00e7a de potencial V<\/b><\/span><\/span><\/span>A<\/b><\/span><\/span><\/sub><\/span>\u00a0\u2013 V<\/b><\/span><\/span><\/span>B<\/b><\/span><\/span><\/sub><\/span>\u00a0entre os pontos terminais A e B em fun\u00e7\u00e3o de\u00a0\u03b5.<\/b><\/span><\/span><\/span><\/p>\n

e as tr\u00eas l\u00e2mpadas id\u00eanticas, L<\/b><\/span><\/span><\/span>\uf020<\/b><\/span><\/span><\/span><\/p>\n

22-(CEFET-MG)<\/b><\/span><\/span><\/span> A chave S, a bateria ideal de fem E <\/b><\/span><\/span><\/span>1<\/b><\/span><\/span><\/sub><\/span>, L<\/b><\/span><\/span><\/span>2<\/b><\/span><\/span><\/sub><\/span>\u00a0e L<\/b><\/span><\/span><\/span>3<\/b><\/span><\/span><\/sub><\/span>\u00a0est\u00e3o ligadas conforme o circuito el\u00e9trico abaixo.<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Quando a chave S \u00e9 fechada, a(s)<\/b><\/span><\/span><\/span><\/p>\n

a) l\u00e2mpadas L<\/b><\/span><\/span><\/span>1<\/b><\/span><\/span><\/sub><\/span>, L<\/b><\/span><\/span><\/span>2<\/b><\/span><\/span><\/sub><\/span>\u00a0e L<\/b><\/span><\/span><\/span>3<\/b><\/span><\/span><\/sub><\/span>\u00a0brilham com a mesma intensidade.\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/b><\/span><\/span><\/span><\/p>\n

b) corrente el\u00e9trica que flui em L<\/b><\/span><\/span><\/span>1<\/b><\/span><\/span><\/sub><\/span>\u00a0\u00e9 o dobro da que flui em L<\/b><\/span><\/span><\/span>2<\/b><\/span><\/span><\/sub><\/span>.\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/b><\/span><\/span><\/span><\/p>\n

c) correntes el\u00e9tricas que fluem nas l\u00e2mpadas L<\/b><\/span><\/span><\/span>2<\/b><\/span><\/span><\/sub><\/span>\u00a0e L<\/b><\/span><\/span><\/span>3<\/b><\/span><\/span><\/sub><\/span>\u00a0s\u00e3o diferentes.\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/b><\/span><\/span><\/span><\/p>\n

d) l\u00e2mpadas L<\/b><\/span><\/span><\/span>1<\/b><\/span><\/span><\/sub><\/span>, L<\/b><\/span><\/span><\/span>2<\/b><\/span><\/span><\/sub><\/span>\u00a0e L<\/b><\/span><\/span><\/span>3<\/b><\/span><\/span><\/sub><\/span>\u00a0est\u00e3o submetidas ao mesmo potencial, E, da bateria.<\/b><\/span><\/span><\/span><\/p>\n

e) pot\u00eancia el\u00e9trica dissipada por L<\/b><\/span><\/span><\/span>2<\/b><\/span><\/span><\/sub><\/span>\u00a0\u00e9 maior do que a pot\u00eancia el\u00e9trica dissipada por L<\/b><\/span><\/span><\/span>1<\/b><\/span><\/span><\/sub><\/span><\/p>\n

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

23- (UFSC-SC)<\/b><\/span><\/span><\/span> Nos circuitos abaixo, A e B s\u00e3o duas l\u00e2mpadas cujos filamentos t\u00eam resist\u00eancias iguais; R \u00e9 a resist\u00eancia de outro dispositivo el\u00e9trico;\u00a0\u03b5\u00a0\u00e9 uma bateria de resist\u00eancia el\u00e9trica desprez\u00edvel; e I \u00e9 um interruptor aberto.<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Sabendo-se que o brilho das l\u00e2mpadas cresce quando a intensidade da corrente el\u00e9trica aumenta, \u00e9 CORRETO afirmar que:<\/b><\/span><\/span><\/span><\/p>\n

01. no circuito 1, a l\u00e2mpada A brilha mais do que a B.<\/b><\/span><\/span><\/span><\/p>\n

02. no circuito 2, as l\u00e2mpadas A e B t\u00eam o mesmo brilho.<\/b><\/span><\/span><\/span><\/p>\n

04. no circuito 3, uma das l\u00e2mpadas brilha mais do que a outra.<\/b><\/span><\/span><\/span><\/p>\n

08. no circuito 4, a l\u00e2mpada B brilha mais do que a A.<\/b><\/span><\/span><\/span><\/p>\n

16. no circuito 5, se o interruptor I for fechado, aumenta o brilho da l\u00e2mpada B.<\/b><\/span><\/span><\/span><\/p>\n

24-(FUVEST-SP)<\/b><\/span><\/span><\/span> A convers\u00e3o de energia solar em energia el\u00e9trica pode ser feita com a utiliza\u00e7\u00e3o de pain\u00e9is constitu\u00eddos por<\/b><\/span><\/span><\/span><\/p>\n

c\u00e9lulas fotovoltaicas que, quando expostas \u00e0 radia\u00e7\u00e3o solar, geram uma diferen\u00e7a de potencial U entre suas faces. Para caracterizar uma dessas c\u00e9lulas (C) de 20 cm<\/b><\/span><\/span><\/span>2<\/b><\/span><\/span><\/sup><\/span>\u00a0de \u00e1rea, sobre a qual incide 1 kW\/m<\/b><\/span><\/span><\/span>2<\/b><\/span><\/span><\/sup><\/span>\u00a0de radia\u00e7\u00e3o solar, foi realizada a medida da diferen\u00e7a de potencial U e da corrente I, variando-se o valor da resist\u00eancia R, conforme o circuito esquematizado na figura abaixo. Os resultados obtidos est\u00e3o apresentados na tabela.<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

a) Fa\u00e7a o gr\u00e1fico da curva I \u00d7 U na figura impressa na folha de respostas.<\/b><\/span><\/span><\/span><\/p>\n

b) Determine o valor da pot\u00eancia m\u00e1xima P<\/b><\/span><\/span><\/span>m<\/b><\/span><\/span><\/sub><\/span>\u00a0que essa c\u00e9lula fornece e o valor da resist\u00eancia R nessa condi\u00e7\u00e3o.<\/b><\/span><\/span><\/span><\/p>\n

c) Determine a efici\u00eancia da c\u00e9lula C para U = 0,3 V.<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

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

25-(UNIFESP-SP)<\/b><\/span><\/span><\/span><\/p>\n

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

Os circuitos el\u00e9tricos A e B esquematizados, utilizam quatro l\u00e2mpadas incandescentes L id\u00eanticas,<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

com especifica\u00e7\u00f5es comerciais de 100W e de 110V, e uma fonte de tens\u00e3o el\u00e9trica de 220V. Os fios condutores, que participam dos dois circuitos el\u00e9tricos, podem ser considerados ideais, isto \u00e9, t\u00eam suas resist\u00eancias \u00f4hmicas desprez\u00edveis.<\/b><\/span><\/span><\/span><\/p>\n

a) Qual o valor da resist\u00eancia \u00f4hmica de cada l\u00e2mpada e a resist\u00eancia \u00f4hmica equivalente de cada circuito el\u00e9trico?<\/b><\/span><\/span><\/span><\/p>\n

b) Calcule a pot\u00eancia dissipada por uma l\u00e2mpada em cada circuito el\u00e9trico, A e B, para indicar o circuito no qual as l\u00e2mpadas apresentar\u00e3o maior ilumina\u00e7\u00e3o.<\/b><\/span><\/span><\/span><\/p>\n

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

26-(PUC-SP)<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

O resistor R<\/b><\/span><\/span><\/span>B<\/b><\/span><\/span><\/sub><\/span>\u00a0dissipa uma pot\u00eancia de 12W. Nesse \u00a0caso, a pot\u00eancia dissipada pelo resistor R<\/b><\/span><\/span><\/span>D<\/b><\/span><\/span><\/sub><\/span>\u00a0vale<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

a) 0,75 W\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/b><\/span><\/span><\/span><\/span><\/p>\n

b) 3,0 W\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/b><\/span><\/span><\/span><\/span><\/p>\n

c) 6,0 W\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/b><\/span><\/span><\/span><\/span><\/p>\n

d) 18,0 W\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/b><\/span><\/span><\/span><\/span><\/p>\n

e) 24,0 W<\/b><\/span><\/span><\/span><\/span><\/p>\n

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

27-(UNESP-SP)<\/b><\/span><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Considere o circuito el\u00e9trico que esquematiza dois modos de liga\u00e7\u00e3o de duas l\u00e2mpadas el\u00e9tricas iguais, com valores nominais<\/b><\/span><\/span><\/span><\/p>\n

de tens\u00e3o e pot\u00eancia el\u00e9trica 60 V e 60 W, respectivamente.<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Modo A \u2013 ambiente totalmente iluminado: a chave Ch, ligada no ponto A, mant\u00e9m as l\u00e2mpadas L<\/b><\/span><\/span><\/span>1<\/b><\/span><\/span><\/sub><\/span>\u00a0e L<\/b><\/span><\/span><\/span>2<\/b><\/span><\/span><\/sub><\/span>\u00a0acesas.<\/b><\/span><\/span><\/span><\/p>\n

Modo B \u2013 ambiente levemente iluminado: a chave Ch, ligada no ponto B, mant\u00e9m apenas a l\u00e2mpada L<\/b><\/span><\/span><\/span>1\u00a0<\/b><\/span><\/span><\/sub><\/span>acesa, com pot\u00eancia menor do que a nominal, devido ao resistor R de resist\u00eancia \u00f4hmica constante estar ligado em s\u00e9rie com L<\/b><\/span><\/span><\/span>1<\/b><\/span><\/span><\/sub><\/span>.<\/b><\/span><\/span><\/span><\/p>\n

Considerando que as l\u00e2mpadas tenham resist\u00eancia el\u00e9trica constante, que os fios tenham resist\u00eancia el\u00e9trica desprez\u00edvel e<\/b><\/span><\/span><\/span><\/p>\n

que a diferen\u00e7a de potencial de 120 V que alimenta o circuito seja constante, calcule a energia el\u00e9trica consumida, em kWh,<\/b><\/span><\/span><\/span><\/p>\n

quando as l\u00e2mpadas permanecem acesas por 4 h, ligadas no modo A \u2013 ambiente totalmente iluminado.<\/b><\/span><\/span><\/span><\/p>\n

Determine a resist\u00eancia el\u00e9trica do resistor R, para que, quando ligada no modo B, a l\u00e2mpada L<\/b><\/span><\/span><\/span>1<\/b><\/span><\/span><\/sub><\/span>\u00a0dissipe uma pot\u00eancia de 15 W.<\/b><\/span><\/span><\/span><\/p>\n

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

28-(FUVEST-SP)<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

A figura ao lado representa, de forma esquem\u00e1tica, a instala\u00e7\u00e3o el\u00e9trica de uma resid\u00eancia, com circuitos de tomadas de uso geral e circuito espec\u00edfico para um chuveiro el\u00e9trico. Nessa resid\u00eancia, os seguintes equipamentos permaneceram ligados durante 3 horas a<\/b><\/span><\/span><\/span><\/p>\n

tomadas de uso geral, conforme o esquema da figura: um aquecedor el\u00e9trico (A<\/b><\/span><\/span><\/span>q<\/b><\/span><\/span><\/sub><\/span>) de 990 W, um ferro de passar roupas de 980 W e duas<\/b><\/span><\/span><\/span><\/p>\n

l\u00e2mpadas, L<\/b><\/span><\/span><\/span>1<\/b><\/span><\/span><\/sub><\/span>\u00a0e L<\/b><\/span><\/span><\/span>2<\/b><\/span><\/span><\/sub><\/span>, de 60 W cada uma.<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Nesse per\u00edodo, al\u00e9m desses equipamentos, um chuveiro el\u00e9trico de 4400 W, ligado ao circuito espec\u00edfico, como indicado na figura, funcionou durante 12 minutos. Para essas condi\u00e7\u00f5es, determine<\/b><\/span><\/span><\/span><\/p>\n

a) a energia total, em kWh, consumida durante esse per\u00edodo de 3 horas;<\/b><\/span><\/span><\/span><\/p>\n

b) a corrente el\u00e9trica que percorre cada um dos fios fase, no circuito prim\u00e1rio do quadro de distribui\u00e7\u00e3o, com todos os equipamentos, inclusive o chuveiro, ligados;<\/b><\/span><\/span><\/span><\/p>\n

c) a corrente el\u00e9trica que percorre o condutor neutro, no circuito prim\u00e1rio do quadro de distribui\u00e7\u00e3o, com todos os equipamentos, inclusive o chuveiro, ligados.<\/b><\/span><\/span><\/span><\/p>\n

Confira a resolu\u00e7\u00e3o comentada<\/span><\/a>\u00a0<\/span><\/h3>\n

 <\/p>\n","protected":false},"excerpt":{"rendered":"

Resolu\u00e7\u00e3o comentada de Circuitos com geradores A resolu\u00e7\u00e3o desse tipo de associa\u00e7\u00f5es \u00e9 feita por etapas at\u00e9 chegar ao resistor equivalente e depois ir retornando e achando o que \u00e9 pedido. \u00a0 01-(UNESP-SP) Dois resistores, um de 20\u2126 e outro de resist\u00eancia R desconhecida, est\u00e3o ligados em s\u00e9rie a uma bateria de 6,0V e resist\u00eancia interna desprez\u00edvel, como mostra a<\/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-1833","page","type-page","status-publish","hentry"],"aioseo_notices":[],"_links":{"self":[{"href":"https:\/\/fisicaevestibular.com.br\/novo\/wp-json\/wp\/v2\/pages\/1833","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=1833"}],"version-history":[{"count":4,"href":"https:\/\/fisicaevestibular.com.br\/novo\/wp-json\/wp\/v2\/pages\/1833\/revisions"}],"predecessor-version":[{"id":11273,"href":"https:\/\/fisicaevestibular.com.br\/novo\/wp-json\/wp\/v2\/pages\/1833\/revisions\/11273"}],"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=1833"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}