{"id":3308,"date":"2017-10-01T13:41:09","date_gmt":"2017-10-01T13:41:09","guid":{"rendered":"http:\/\/fisicaevestibular.com.br\/novo\/?page_id=3308"},"modified":"2024-06-30T00:17:41","modified_gmt":"2024-06-30T00:17:41","slug":"eletrodinamica-2014-2013","status":"publish","type":"page","link":"https:\/\/fisicaevestibular.com.br\/novo\/vestibulares-recentes\/eletricidade\/eletrodinamica-2014-2013\/","title":{"rendered":"Eletrodin\u00e2mica – 2014 \u2013 2013"},"content":{"rendered":"

Vestibulares Recentes<\/span><\/span><\/span><\/h1>\n

Eletrodin\u00e2mica – 2014 \u2013 2013<\/span><\/span><\/span><\/p>\n

01-(UNISINOS-RS-014)<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Uma l\u00e2mpada de lanterna\u00a0apresenta as\u00a0se\u00adguintes especifica\u00e7\u00f5es: 12V \u2013 24W.<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Ao aplicar-se\u00a06V \u00e0 l\u00e2mpada, a\u00a0corrente el\u00e9trica\u00a0que nela circula \u00e9 de ……………… A, e a\u00a0pot\u00eancia que dissipa\u00a0\u00e9 de ……………… W.<\/b><\/span><\/span><\/span><\/p>\n

As\u00a0lacunas s\u00e3o corretamente preenchidas, respec\u00adtivamente, por<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

02-(UNIFESP-SP-014)<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Para compor sua decora\u00e7\u00e3o de Natal, um comerciante decide construir uma estrela para pendurar na fachada de sua loja. Para isso, utilizar\u00e1 um material que, quando\u00a0percorrido por corrente el\u00e9trica, brilhe emitindo luz colorida.\u00a0Ele tem \u00e0 sua disposi\u00e7\u00e3o\u00a0barras de diferentes cores desse material,\u00a0cada uma\u00a0com\u00a0resist\u00eancia el\u00e9trica constante\u00a0R = 20 \u03a9.<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Utilizando\u00a0dez\u00a0dessas barras, ele montou uma estrela e conectou os pontos A e B a um\u00a0gerador ideal\u00a0de\u00a0for\u00e7a eletromotriz constante e igual a\u00a0120 V.<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Considerando desprez\u00edveis as resist\u00eancias el\u00e9tricas dos fios utilizados e das conex\u00f5es feitas, calcule:<\/b><\/span><\/span><\/span><\/p>\n

a)\u00a0<\/b><\/span><\/span><\/span>a\u00a0resist\u00eancia equivalente, em ohms, da estrela.<\/b><\/span><\/span><\/span><\/p>\n

b)\u00a0<\/b><\/span><\/span><\/span>a\u00a0pot\u00eancia el\u00e9trica, em watts, dissipada em conjunto pelas pontas de cores\u00a0laranja (CAD), azul (DEF) e vermelha (FBG)\u00a0da estrela, quando ela se encontrar acesa.<\/b><\/span><\/span><\/span><\/p>\n

03-(UNESP-SP-014)<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

O circuito\u00a0representado na figura \u00e9 utilizado\u00a0para obter\u00a0diferentes intensidades luminosas com a mesma l\u00e2mpada L.<\/b><\/span><\/span><\/span><\/p>\n

A\u00a0chave Ch pode ser ligada ao ponto A ou ao ponto B do circuito. Quando\u00a0ligada em B, a\u00a0l\u00e2mpada L dissipa uma\u00a0pot\u00eancia de 60 W\u00a0e o\u00a0amper\u00edmetro ideal\u00a0\"\"\u00a0indica uma\u00a0corrente el\u00e9trica de intensidade 2 A.<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Considerando que o\u00a0gerador\u00a0tenha\u00a0for\u00e7a eletromotriz constante E = 100 V\u00a0e\u00a0resist\u00eancia interna desprez\u00edvel, que os resistores e a l\u00e2mpada tenham resist\u00eancias constantes e que os fios de liga\u00e7\u00e3o e as conex\u00f5es sejam ideais,\u00a0<\/b><\/span><\/span><\/span>calcule<\/b><\/span><\/span><\/span> o valor da resist\u00eancia\u00a0R<\/b><\/span><\/span><\/span>L<\/b><\/span><\/span><\/sub><\/span>\u00a0da l\u00e2mpada, em ohms, e a\u00a0energia\u00a0dissipada pelo circuito, em joules, se ele permanecer\u00a0ligado durante dois minutos com a chave na posi\u00e7\u00e3o A.<\/b><\/span><\/span><\/span><\/p>\n

04-(ACAFE-SC-014)<\/b><\/span><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Em uma situa\u00e7\u00e3o cotidiana, uma pessoa\u00a0liga duas l\u00e2mpadas incandescentes em paralelo em uma rede de 220V. As l\u00e2mpadas apresentam\u00a0certa intensidade luminosa (brilho), sendo que a\u00a0l\u00e2mpada<\/b><\/span><\/span><\/span><\/p>\n

2 tem um filamento de mesmo material, mesmo comprimento, mas \u00e9 mais grosso que o filamento<\/b><\/span><\/span><\/span><\/p>\n

da l\u00e2mpada 1.<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Nessas condi\u00e7\u00f5es, a\u00a0alternativa\u00a0correta\u00a0\u00e9:<\/b><\/span><\/span><\/span><\/p>\n

A)\u00a0<\/b><\/span><\/span><\/span>Desligando a l\u00e2mpada L<\/b><\/span><\/span><\/span>1<\/b><\/span><\/span><\/sub><\/span>, a l\u00e2mpada L<\/b><\/span><\/span><\/span>2<\/b><\/span><\/span><\/sub><\/span>\u00a0diminui o seu brilho.<\/b><\/span><\/span><\/span><\/p>\n

B)\u00a0<\/b><\/span><\/span><\/span>A l\u00e2mpada L<\/b><\/span><\/span><\/span>1<\/b><\/span><\/span><\/sub><\/span>\u00a0brilha mais que a l\u00e2mpada L<\/b><\/span><\/span><\/span>2<\/b><\/span><\/span><\/sub><\/span>.<\/b><\/span><\/span><\/span><\/p>\n

C)\u00a0<\/b><\/span><\/span><\/span>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>\u00a0tem o mesmo brilho.<\/b><\/span><\/span><\/span><\/p>\n

D)\u00a0<\/b><\/span><\/span><\/span>A l\u00e2mpada L<\/b><\/span><\/span><\/span>2<\/b><\/span><\/span><\/sub><\/span>\u00a0brilha mais que a l\u00e2mpada L<\/b><\/span><\/span><\/span>1<\/b><\/span><\/span><\/sub><\/span>.<\/b><\/span><\/span><\/span><\/p>\n

05-(UNESP-SP-014)<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Para compor a\u00a0decora\u00e7\u00e3o de um ambiente,\u00a0duas l\u00e2mpadas 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>, com\u00a0valores nominais\u00a0(100 V \u2013 100 W),\u00a0devem ser ligadas em\u00a0paralelo a uma fonte de tens\u00e3o constante de\u00a0200 V. Deseja-se que\u00a0L<\/b><\/span><\/span><\/span>1<\/b><\/span><\/span><\/sub><\/span>\u00a0brilhe\u00a0com uma\u00a0pot\u00eancia de 100 W\u00a0e que\u00a0L<\/b><\/span><\/span><\/span>2<\/b><\/span><\/span><\/sub><\/span>\u00a0brilhe\u00a0com uma\u00a0pot\u00eancia de 64 W.\u00a0Para<\/b><\/span><\/span><\/span><\/p>\n

que as l\u00e2mpadas n\u00e3o queimem,\u00a0dois resistores \u00f4hmicos, R<\/b><\/span><\/span><\/span>1\u00a0<\/b><\/span><\/span><\/sub><\/span>e R<\/b><\/span><\/span><\/span>2<\/b><\/span><\/span><\/sub><\/span>, com valores convenientes,\u00a0s\u00e3o\u00a0ligados em\u00a0s\u00e9rie com<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/sub><\/span>as respectivas l\u00e2mpadas, conforme o esquema representado<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/sub><\/span>na figura.<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Considerando todos os fios utilizados na liga\u00e7\u00e3o como ideais e que as\u00a0l\u00e2mpadas estejam acesas\u00a0e\u00a0brilhando com as pot\u00eancias desejadas, \u00e9 correto afirmar que os\u00a0valores das resist\u00eancias 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,\u00a0s\u00e3o, respectivamente, iguais a<\/b><\/span><\/span><\/span><\/p>\n

(A) 200 e 100. <\/b><\/span><\/span><\/span><\/p>\n

(B) 200 e 150. <\/b><\/span><\/span><\/span><\/p>\n

(C) 100 e 150. <\/b><\/span><\/span><\/span><\/p>\n

(D) 100 e 300. <\/b><\/span><\/span><\/span><\/p>\n

(E) 100 e 200.<\/b><\/span><\/span><\/span><\/p>\n

06-(AFA-014)<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Disp\u00f5e-se de duas pilhas id\u00eanticas de f.e.m \u03b5 e resist\u00eancia interna r constante e de um reostato, cuja resist\u00eancia el\u00e9trica R varia de zero at\u00e9 6 r. Essas pilhas podem ser associadas em s\u00e9rie ou em paralelo, conforme ilustram as figuras I e II, respectivamente.<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

O gr\u00e1fico que melhor representa a pot\u00eancia P dissipada pelo reostato, para cada uma das associa\u00e7\u00f5es, em fun\u00e7\u00e3o da resist\u00eancia R \u00e9<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

07-(UFSCAR-SP-014)<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Um professor pede a seus alunos que tabelem as leituras do\u00a0volt\u00edmetro\u00a0e do\u00a0amper\u00edmetro\u00a0associados aos circuitos 1, 2 e 3, quando esses circuitos s\u00e3o conectados, um de cada vez, aos terminais A e B de um\u00a0gerador ideal. Os resistores utilizados t\u00eam\u00a0igual\u00a0valor \u00f4hmico.<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Ap\u00f3s a s\u00e9rie de leituras, os alunos constru\u00edram a seguinte tabela:<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

A partir da an\u00e1lise da tabela, os alunos puderam concluir acertadamente que, em\u00a0circuitos s\u00e9rie, \u00e0 medida que se\u00a0aumenta o n\u00famero de resistores associados, a resist\u00eancia equivalente da associa\u00e7\u00e3o\u00a0_________ ,\u00a0a diferen\u00e7a de potencial entre os extremos de um mesmo resistor\u00a0____________ e a intensidade de\u00a0corrente el\u00e9trica no\u00a0circuito___________ .<\/b><\/span><\/span><\/span><\/p>\n

Assinale a alternativa que preenche, correta e respectivamente, as lacunas do texto.<\/b><\/span><\/span><\/span><\/p>\n

(A) diminui \u2013 diminui \u2013 diminui<\/b><\/span><\/span><\/span><\/p>\n

(B) diminui \u2013 aumenta \u2013 aumenta<\/b><\/span><\/span><\/span><\/p>\n

(C) aumenta \u2013 aumenta \u2013 aumenta<\/b><\/span><\/span><\/span><\/p>\n

(D) aumenta \u2013 aumenta \u2013 diminui<\/b><\/span><\/span><\/span><\/p>\n

(E) aumenta \u2013 diminui \u2013 diminui<\/b><\/span><\/span><\/span><\/p>\n

08-(UERJ-RJ-014)<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Cinco resistores de\u00a0mesma resist\u00eancia\u00a0R\u00a0est\u00e3o conectados \u00e0 bateria\u00a0ideal E\u00a0de um autom\u00f3vel,<\/b><\/span><\/span><\/span><\/p>\n

conforme mostra o esquema:<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Inicialmente, a bateria fornece ao circuito uma pot\u00eancia\u00a0P<\/b><\/span><\/span><\/span>i<\/b><\/span><\/span><\/sub><\/span>.\u00a0Ao\u00a0estabelecer um curto-circuito<\/b><\/span><\/span><\/span><\/p>\n

entre os pontos M e N, a pot\u00eancia fornecida \u00e9 igual a P<\/b><\/span><\/span><\/span>f<\/b><\/span><\/span><\/sub><\/span>.<\/b><\/span><\/span><\/span><\/p>\n

A raz\u00e3o \u00e9\u00a0Pf\/Pi\u00a0\u00e9 dada por:<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

09-(FUVEST-SP-014)<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

A\u00a0curva\u00a0caracter\u00edstica\u00a0de\u00a0uma\u00a0l\u00e2mpada\u00a0do\u00a0tipo\u00a0led\u00a0(diodo\u00a0emissor\u00a0de\u00a0luz)\u00a0\u00e9 mostrada no gr\u00e1fico.\u00a0Essa\u00a0l\u00e2mpada\u00a0e\u00a0um\u00a0resistor\u00a0de\u00a0resist\u00eancia\u00a0 R\u00a0 est\u00e3o\u00a0 ligados\u00a0 em\u00a0 s\u00e9rie\u00a0 a\u00a0 uma\u00a0 bateria\u00a0 de\u00a0 4,5\u00a0V,\u00a0<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

como\u00a0representado\u00a0na\u00a0figura\u00a0ao\u00a0lado do gr\u00e1fico.\u00a0Nessa\u00a0condi\u00e7\u00e3o,\u00a0a\u00a0tens\u00e3o\u00a0na\u00a0l\u00e2mpada\u00a0\u00e9\u00a02,5\u00a0V.\u00a0\u00a0<\/b><\/span><\/span><\/span><\/p>\n

a) <\/b><\/span><\/span><\/span>Qual\u00a0\u00e9\u00a0o\u00a0valor\u00a0da\u00a0corrente\u00a0i<\/b><\/span><\/span><\/span>R<\/b><\/span><\/span><\/sub><\/span>\u00a0no\u00a0resistor?\u00a0<\/b><\/span><\/span><\/span><\/p>\n

b) <\/b><\/span><\/span><\/span>Determine\u00a0o\u00a0valor\u00a0da\u00a0resist\u00eancia\u00a0R.\u00a0<\/b><\/span><\/span><\/span><\/p>\n

c) <\/b><\/span><\/span><\/span>A\u00a0bateria\u00a0de\u00a04,5\u00a0V\u00a0\u00e9\u00a0substitu\u00edda\u00a0por\u00a0outra\u00a0de\u00a03\u00a0V,\u00a0que\u00a0fornece\u00a060\u00a0mW\u00a0de\u00a0pot\u00eancia\u00a0ao\u00a0circuito,\u00a0sem\u00a0<\/b><\/span><\/span><\/span><\/p>\n

que\u00a0sejam\u00a0trocados\u00a0a\u00a0l\u00e2mpada\u00a0e\u00a0o\u00a0resistor.\u00a0Nessas\u00a0condi\u00e7\u00f5es,\u00a0qual\u00a0\u00e9\u00a0a\u00a0pot\u00eancia\u00a0P<\/b><\/span><\/span><\/span>R<\/b><\/span><\/span><\/sub><\/span>\u00a0dissipada\u00a0no\u00a0<\/b><\/span><\/span><\/span><\/p>\n

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

\"\"<\/p>\n

10-(FUVEST-SP-014)<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Dois fios met\u00e1licos, F<\/b><\/span><\/span><\/span>1\u00a0<\/b><\/span><\/span><\/sub><\/span>e F<\/b><\/span><\/span><\/span>2<\/b><\/span><\/span><\/sub><\/span>, cil\u00edndricos, do mesmo material de resistividade \u03c1, de se\u00e7\u00f5es transversais de \u00e1reas, respectivamente, A<\/b><\/span><\/span><\/span>1\u00a0<\/b><\/span><\/span><\/sub><\/span>e A<\/b><\/span><\/span><\/span>2<\/b><\/span><\/span><\/sub><\/span>=2A<\/b><\/span><\/span><\/span>1<\/b><\/span><\/span><\/sub><\/span>, t\u00eam comprimento L e s\u00e3o emendados, como ilustra a figura abaixo.<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

O sistema formado pelos fios \u00e9 conectado a uma bateria de tens\u00e3o V.<\/b><\/span><\/span><\/span><\/p>\n

Nessas condi\u00e7\u00f5es, a diferen\u00e7a de potencial V<\/b><\/span><\/span><\/span>1<\/b><\/span><\/span><\/sub><\/span>, entre as extremidades de F<\/b><\/span><\/span><\/span>1<\/b><\/span><\/span><\/sub><\/span>, e V<\/b><\/span><\/span><\/span>2<\/b><\/span><\/span><\/sub><\/span>, entre as de F<\/b><\/span><\/span><\/span>2<\/b><\/span><\/span><\/sub><\/span>, s\u00e3o tais que<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

11-(UNESP-SP-014)<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Dois resistores \u00f4hmicos, R<\/b><\/span><\/span><\/span>1<\/b><\/span><\/span><\/sub><\/span>\u00a0e R<\/b><\/span><\/span><\/span>2<\/b><\/span><\/span><\/sub><\/span>, podem ser associados em s\u00e9rie ou em paralelo. A resist\u00eancia equivalente quando s\u00e3o associados em s\u00e9rie \u00e9 R<\/b><\/span><\/span><\/span>S\u00a0<\/b><\/span><\/span><\/sub><\/span>e quando s\u00e3o associados em paralelo \u00e9 R<\/b><\/span><\/span><\/span>p<\/b><\/span><\/span><\/sub><\/span>.<\/b><\/span><\/span><\/span><\/p>\n

No gr\u00e1fico, a curva S representa a varia\u00e7\u00e3o da diferen\u00e7a de potencial el\u00e9trico entre os extremos da associa\u00e7\u00e3o dos dois resistores em s\u00e9rie, em fun\u00e7\u00e3o da intensidade de corrente el\u00e9trica que atravessa a associa\u00e7\u00e3o de resist\u00eancia equivalente R<\/b><\/span><\/span><\/span>S<\/b><\/span><\/span><\/sub><\/span>\u00a0, e a curva P representa a varia\u00e7\u00e3o da diferen\u00e7a de potencial el\u00e9trico entre os extremos da associa\u00e7\u00e3o dos dois resistores em paralelo R<\/b><\/span><\/span><\/span>p<\/b><\/span><\/span><\/sub><\/span>, em fun\u00e7\u00e3o da intensidade da corrente el\u00e9trica que atravessa a associa\u00e7\u00e3o de resist\u00eancia equivalente R<\/b><\/span><\/span><\/span>p<\/b><\/span><\/span><\/sub><\/span>.<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Considere a associa\u00e7\u00e3o seguinte, constitu\u00edda por dois resistores R<\/b><\/span><\/span><\/span>1<\/b><\/span><\/span><\/sub><\/span>\u00a0e dois resistores R<\/b><\/span><\/span><\/span>2<\/b><\/span><\/span><\/sub><\/span>.<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

De acordo com as informa\u00e7\u00f5es e desprezando a resist\u00eancia el\u00e9trica dos fios de liga\u00e7\u00e3o,\u00a0calcule a resist\u00eancia equivalente da associa\u00e7\u00e3o representada na figura e 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>\u00a0, ambos em ohms.<\/b><\/span><\/span><\/span><\/p>\n

12-(UNICAMP-SP-014)<\/b><\/span><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

No fen\u00f4meno de \u201cMagnetoimped\u00e2ncia gigante\u201d, a resist\u00eancia el\u00e9trica de determinado material pelo qual circula uma corrente alternada de\u00a0frequ\u00eancia\u00a0<\/b><\/span><\/span><\/span>f\u00a0<\/b><\/i><\/span><\/span><\/span>varia com a aplica\u00e7\u00e3o de\u00a0um campo magn\u00e9tico\u00a0<\/b><\/span><\/span><\/span>H<\/b><\/i><\/span><\/span><\/span>. O<\/b><\/span><\/span><\/span><\/p>\n

gr\u00e1fico da figura 1\u00a0mostra a\u00a0resist\u00eancia el\u00e9trica\u00a0de determinado fio de\u00a0resistividade el\u00e9trica \u03c1=64,8.10<\/b><\/span><\/span><\/span>-8<\/b><\/span><\/span><\/sup><\/span>\u00a0\u03a9m<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

em fun\u00e7\u00e3o da\u00a0frequ\u00eancia\u00a0<\/b><\/span><\/span><\/span>f\u00a0<\/b><\/i><\/span><\/span><\/span>da corrente el\u00e9trica alternada que circula por esse fio, para diferentes valores de\u00a0<\/b><\/span><\/span><\/span>H\u00a0<\/b><\/i><\/span><\/span><\/span>.<\/b><\/span><\/span><\/span><\/p>\n

a) <\/b><\/span><\/span><\/span>Como podemos ver na figura 1, o valor da resist\u00eancia el\u00e9trica do fio para\u00a0<\/b><\/span><\/span><\/span>f\u00a0<\/b><\/i><\/span><\/span><\/span>=0Hz \u00e9\u00a0<\/b><\/span><\/span><\/span>R=<\/b><\/i><\/span><\/span><\/span>1,5\u2126. Calcule<\/b><\/span><\/span><\/span><\/p>\n

o\u00a0comprimento\u00a0<\/b><\/span><\/span><\/span>L\u00a0<\/b><\/i><\/span><\/span><\/span>desse fio, cuja\u00a0\u00e1rea de se\u00e7\u00e3o transversal vale\u00a0<\/b><\/span><\/span><\/span>A=<\/b><\/i><\/span><\/span><\/span>1,296 10<\/b><\/span><\/span><\/span>-8<\/b><\/span><\/span><\/sup><\/span>\u00a0m<\/b><\/span><\/span><\/span>2<\/b><\/span><\/span><\/sup><\/span>.<\/b><\/span><\/span><\/span><\/p>\n

b) <\/b><\/span><\/span><\/span>Para altas frequ\u00eancias, a corrente el\u00e9trica alternada n\u00e3o est\u00e1 uniformemente distribu\u00edda na se\u00e7\u00e3o reta do fio, mas sim confinada em uma regi\u00e3o pr\u00f3xima a sua superf\u00edcie. Esta regi\u00e3o \u00e9 determinada pelo comprimento de penetra\u00e7\u00e3o, que \u00e9 dado por\u00a0\"\"=k\u221a(\u03c1\/\u03bc<\/b><\/span><\/span><\/span>r<\/b><\/span><\/span><\/sub><\/span>.f), em que \u03c1 \u00e9 a resistividade do fio,\u00a0<\/b><\/span><\/span><\/span>f\u00a0<\/b><\/i><\/span><\/span><\/span>\u00e9 a frequ\u00eancia da corrente el\u00e9trica alternada, \u03bc<\/b><\/span><\/span><\/span>r<\/b><\/span><\/span><\/sub><\/span>\u00a0\u00e9 a permeabilidade magn\u00e9tica relativa do fio e k=500\u221a(mHz\/\u2126).<\/b><\/span><\/span><\/span><\/p>\n

Sabendo que \u03bc<\/b><\/span><\/span><\/span>r<\/b><\/span><\/span><\/sub><\/span>\u00a0varia com o\u00a0campo magn\u00e9tico aplicado\u00a0<\/b><\/span><\/span><\/span>H\u00a0<\/b><\/i><\/span><\/span><\/span>, como mostra a figura 2, e que, para o<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

particular valor de f=8MHz temos\u00a0<\/b><\/span><\/span><\/span>R<\/b><\/i><\/span><\/span><\/span>\u22484\u2126, calcule o valor de\u00a0\"\"para essa situa\u00e7\u00e3o.<\/b><\/span><\/span><\/span><\/p>\n

13-(CEDERJ-RJ-014)<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

O circuito mostra\u00a0tr\u00eas elementos resistivos de resist\u00eancias\u00a0R<\/b><\/span><\/span><\/span>1<\/b><\/span><\/span><\/sub><\/span>, R<\/b><\/span><\/span><\/span>2<\/b><\/span><\/span><\/sub><\/span>\u00a0e R<\/b><\/span><\/span><\/span>3<\/b><\/span><\/span><\/sub><\/span>\u00a0ligados a uma fonte de tens\u00e3o<\/b><\/span><\/span><\/span><\/p>\n

V\u00a0por fios condutores de resist\u00eancia desprez\u00edvel. Os valores das\u00a0diferen\u00e7as de potencial\u00a0entre os terminais desses resistores e das\u00a0correntes el\u00e9tricas que fluem atrav\u00e9s deles\u00a0s\u00e3o, respectivamente,\u00a0V<\/b><\/span><\/span><\/span>1<\/b><\/span><\/span><\/sub><\/span>\u00a0= 8,0V e I<\/b><\/span><\/span><\/span>1<\/b><\/span><\/span><\/sub><\/span>\u00a0= 4,0A, V<\/b><\/span><\/span><\/span>2<\/b><\/span><\/span><\/sub><\/span>\u00a0= 4,0V e I<\/b><\/span><\/span><\/span>2<\/b><\/span><\/span><\/sub><\/span>\u00a0= 2,0A, V<\/b><\/span><\/span><\/span>3<\/b><\/span><\/span><\/sub><\/span>\u00a0= 4,0V e I<\/b><\/span><\/span><\/span>3<\/b><\/span><\/span><\/sub><\/span>\u00a0= 2,0A.<\/b><\/span><\/span><\/span><\/p>\n

Assinale a alternativa que descreve corretamente a\u00a0compara\u00e7\u00e3o entre as resist\u00eancias\u00a0R<\/b><\/span><\/span><\/span>1<\/b><\/span><\/span><\/sub><\/span>, R<\/b><\/span><\/span><\/span>2<\/b><\/span><\/span><\/sub><\/span>\u00a0e R<\/b><\/span><\/span><\/span>3<\/b><\/span><\/span><\/sub><\/span>\u00a0e entre\u00a0as pot\u00eancias dissipadas, respectivamente, pelo resistor R<\/b><\/span><\/span><\/span>1<\/b><\/span><\/span><\/sub><\/span>\u00a0(pot\u00eancia P<\/b><\/span><\/span><\/span>1<\/b><\/span><\/span><\/sub><\/span>) e pelo conjunto\u00a0formado por R<\/b><\/span><\/span><\/span>2<\/b><\/span><\/span><\/sub><\/span>\u00a0e R<\/b><\/span><\/span><\/span>3<\/b><\/span><\/span><\/sub><\/span>\u00a0(pot\u00eancia P<\/b><\/span><\/span><\/span>23<\/b><\/span><\/span><\/sub><\/span>).<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

\"\"<\/p>\n

14-(UERJ-RJ-014)<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

No circuito, uma bateria B est\u00e1 conectada a tr\u00eas resistores de resist\u00eancias R<\/b><\/span><\/span><\/span>1<\/b><\/span><\/span><\/sub><\/span>, R<\/b><\/span><\/span><\/span>2<\/b><\/span><\/span><\/sub><\/span>\u00a0e R<\/b><\/span><\/span><\/span>3<\/b><\/span><\/span><\/sub><\/span>:<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Sabe-se que R<\/b><\/span><\/span><\/span>2<\/b><\/span><\/span><\/sub><\/span>\u00a0= R<\/b><\/span><\/span><\/span>3<\/b><\/span><\/span><\/sub><\/span>=2R<\/b><\/span><\/span><\/span>1<\/b><\/span><\/span><\/sub><\/span>.<\/b><\/span><\/span><\/span><\/p>\n

A rela\u00e7\u00e3o entre as pot\u00eancias P<\/b><\/span><\/span><\/span>1<\/b><\/span><\/span><\/sub><\/span>, P<\/b><\/span><\/span><\/span>2<\/b><\/span><\/span><\/sub><\/span>\u00a0e P<\/b><\/span><\/span><\/span>3<\/b><\/span><\/span><\/sub><\/span>, respectivamente associadas a R<\/b><\/span><\/span><\/span>1<\/b><\/span><\/span><\/sub><\/span>. R<\/b><\/span><\/span><\/span>2<\/b><\/span><\/span><\/sub><\/span>\u00a0e R<\/b><\/span><\/span><\/span>3<\/b><\/span><\/span><\/sub><\/span>, pode ser expressa como:<\/b><\/span><\/span><\/span><\/p>\n

(A) P<\/b><\/span><\/span><\/span>1<\/b><\/span><\/span><\/sub><\/span>= P<\/b><\/span><\/span><\/span>2<\/b><\/span><\/span><\/sub><\/span>= P<\/b><\/span><\/span><\/span>3<\/b><\/span><\/span><\/sub><\/span>\u00a0<\/b><\/span><\/span><\/span><\/p>\n

(B) 2P<\/b><\/span><\/span><\/span>1<\/b><\/span><\/span><\/sub><\/span>= P<\/b><\/span><\/span><\/span>2<\/b><\/span><\/span><\/sub><\/span>= P<\/b><\/span><\/span><\/span>3<\/b><\/span><\/span><\/sub><\/span>\u00a0<\/b><\/span><\/span><\/span><\/p>\n

(C) 4P<\/b><\/span><\/span><\/span>1<\/b><\/span><\/span><\/sub><\/span>= P<\/b><\/span><\/span><\/span>2<\/b><\/span><\/span><\/sub><\/span>= P<\/b><\/span><\/span><\/span>3<\/b><\/span><\/span><\/sub><\/span>\u00a0<\/b><\/span><\/span><\/span><\/p>\n

(D) P<\/b><\/span><\/span><\/span>1<\/b><\/span><\/span><\/sub><\/span>= 2P<\/b><\/span><\/span><\/span>2<\/b><\/span><\/span><\/sub><\/span>= 2P<\/b><\/span><\/span><\/span>3<\/b><\/span><\/span><\/sub><\/span><\/p>\n

15-(MACKENZIE-SP-014)<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

No circuito desenhado abaixo, a\u00a0intensidade de corrente el\u00e9trica\u00a0cont\u00ednua que passa pelo\u00a0resistor de 50 \u03a9\u00a0\u00e9<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

de 80 mA. A\u00a0for\u00e7a eletromotriz\u00a0\u03b5\u00a0do gerador\u00a0ideal \u00e9 igual a<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

16-(MACKENZIE-SP-014)<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Duas pilhas el\u00e9tricas de\u00a0resist\u00eancias internas\u00a0nulas, associadas em\u00a0s\u00e9rie,\u00a0\u201calimentam\u201d a\u00a0l\u00e2mpada<\/b><\/span><\/span><\/span><\/p>\n

incandescente\u00a0ilustrada na figura ao abaixo.<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

O\u00a0amper\u00edmetro ideal A\u00a0indica a intensidade de\u00a0corrente el\u00e9trica 0,50 A, quando o\u00a0volt\u00edmetro V, tamb\u00e9m ideal,<\/b><\/span><\/span><\/span> <\/b>indica a\u00a0d.d.p. de 3,00 V. Sabendo-se que a\u00a0pot\u00eancia dissipada\u00a0por efeito Joule no filamento da l\u00e2mpada<\/b><\/span><\/span><\/span> <\/b>corresponde a\u00a01\/4 do valor nominal, indicado pelo fabricante, pode-se afirmar que os\u00a0valores m\u00e1ximos<\/b><\/span><\/span><\/span> <\/b>nominais, de\u00a0pot\u00eancia e tens\u00e3o el\u00e9trica especificados na l\u00e2mpada\u00a0(pot\u00eancia \u2014 d.d.p.),\u00a0s\u00e3o<\/b><\/span><\/span><\/span><\/p>\n

a) 1,50 W \u2014 3,00 V <\/b><\/span><\/span><\/span><\/span><\/p>\n

b) 3,00 W \u2014 3,00 V <\/b><\/span><\/span><\/span><\/span><\/p>\n

c) 3,00 W \u2014 6,00 V <\/b><\/span><\/span><\/span><\/span><\/p>\n

d) 6,00 W \u2014 6,00 V<\/b><\/span><\/span><\/span><\/span><\/p>\n

e) 6,00 W \u2014 3,00 V<\/b><\/span><\/span><\/span><\/p>\n

Corrente el\u00e9trica<\/b><\/span><\/span><\/span><\/p>\n

37-(UNICAMP-SP-013)<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Um carro el\u00e9trico \u00e9 uma alternativa aos ve\u00edculos com motor a combust\u00e3o interna. Qual \u00e9 a autonomia <\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

de um carro el\u00e9trico que se desloca a 60km\/h, se a corrente el\u00e9trica empregada nesta velocidade \u00e9 igual a 50A e a carga m\u00e1xima armazenada em suas baterias \u00e9 q = 75Ah?<\/b><\/span><\/span><\/span><\/p>\n

a) 40,0km. \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0b) 62,5km.\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 c) 90,0km.\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 d) 160,0km<\/b><\/span><\/span><\/span><\/p>\n

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

38-(ENEM-MEC-012)<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Para ligar ou desligar uma mesma l\u00e2mpada a partir de dois interruptores, conectam-se os interruptores para que a mudan\u00e7a de posi\u00e7\u00e3o de um deles fa\u00e7a ligar ou desligar a l\u00e2mpada, n\u00e3o importando qual a posi\u00e7\u00e3o do outro. <\/b><\/span><\/span><\/span><\/p>\n

Esta liga\u00e7\u00e3o \u00e9 conhecida como interruptores paralelos. Este interruptor \u00e9 uma chave de duas posi\u00e7\u00f5es constitu\u00edda por um polo e dois terminais, conforme mostrado nas figuras de um mesmo interruptor. <\/b><\/span><\/span><\/span><\/p>\n

Na Posi\u00e7\u00e3o I a chave conecta o polo ao terminal superior, e na Posi\u00e7\u00e3o II a chave o conecta ao terminal inferior<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

O circuito que cumpre a finalidade de funcionamento descrita no texto \u00e9:<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

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

Pot\u00eancia el\u00e9trica \u2013 Energia el\u00e9trica<\/b><\/span><\/span><\/span><\/p>\n

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

51-(FGV-RJ-013)<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Um grupo de estudantes, em aula de laborat\u00f3rio de F\u00edsica, mergulhou o resistor de um aquecedor el\u00e9trico, ligado a uma fonte de tens\u00e3o de 120 V, em um recipiente, termicamente isolado, contendo \u00e1gua. Mediram a temperatura da \u00e1gua em fun\u00e7\u00e3o do tempo e verificaram que, em 2 minutos, a temperatura variou de 20\u00b0C a 80\u00b0C. A partir dos resultados obtidos, constru\u00edram o gr\u00e1fico apresentado na figura abaixo, da quantidade de calor Q, em calorias, fornecida \u00e0 \u00e1gua em fun\u00e7\u00e3o do instante t, a partir do mergulho do resistor na \u00e1gua, em minutos. Dados: 1cal=4J e c<\/b><\/span><\/span><\/span>\u00e1gua<\/b><\/span><\/span><\/sub><\/span>=1cal\/g<\/b><\/span><\/span><\/span>o<\/b><\/span><\/span><\/sup><\/span>C<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Os valores da resist\u00eancia el\u00e9trica do aquecedor e da massa de \u00e1gua aquecida s\u00e3o, respectivamente, iguais a:<\/b><\/span><\/span><\/span><\/p>\n

A. 72 \u03a9 e 400 g\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 <\/b><\/span><\/span><\/span><\/p>\n

B. 18 \u03a9 e 400 g\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 <\/b><\/span><\/span><\/span><\/p>\n

C. 72 \u03a9 e 200 g\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 <\/b><\/span><\/span><\/span><\/p>\n

D. 18 \u03a9 e 200 g\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 <\/b><\/span><\/span><\/span><\/p>\n

E. 750 m \u03a9 e 16,7 g<\/b><\/span><\/span><\/span><\/p>\n

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

52-(PUC-MG-013)<\/b><\/span><\/span><\/span><\/p>\n

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

A gera\u00e7\u00e3o de energia el\u00e9trica atrav\u00e9s da luz se d\u00e1 pelo uso de c\u00e9lulas fotossens\u00edveis, chamadas de <\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

\u00a0c\u00e9lulas solares fotovoltaicas. As c\u00e9lulas fotovoltaicas em geral s\u00e3o constitu\u00eddas de materiais semicondutores, com caracter\u00edsticas cristalinas e depositadas sobre s\u00edlica. Essas c\u00e9lulas, agrupadas em m\u00f3dulos ou pain\u00e9is, comp\u00f5em os pain\u00e9is solares fotovoltaicos. A quantidade de energia gerada por um painel solar \u00e9 limitada pela sua pot\u00eancia, ou seja, um painel de 145 W, com seis horas \u00fateis de sol, gera aproximadamente 810 Watts por dia.<\/b><\/span><\/span><\/span><\/p>\n

Fonte http:\/\/www.sunlab.com.br\/Energia_solar_Sunlab.htm<\/b><\/span><\/span><\/span><\/p>\n

Assinale o n\u00famero de horas em que o painel acima consegue manter acesa uma l\u00e2mpada fluorescente de 9 Watts.<\/b><\/span><\/span><\/span><\/p>\n

a) 9 h \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0b) 18 h \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\u00a0c) 58 h \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\u00a0d) 90 h<\/b><\/span><\/span><\/span><\/p>\n

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

53-(UNICAMP-SP-013)<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Na reciclagem de embalagens de alum\u00ednio, usam-se apenas 5% da energia despendida na sua <\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

fabrica\u00e7\u00e3o a partir do min\u00e9rio de bauxita. No entanto, n\u00e3o se deve esquecer a enorme quantidade de energia envolvida nessa fabrica\u00e7\u00e3o (3,6.10<\/b><\/span><\/span><\/span>6<\/b><\/span><\/span><\/sup><\/span>\u00a0joules por latinha), al\u00e9m do fato de que a bauxita cont\u00e9m (em m\u00e9dia) 55% de \u00f3xido de alum\u00ednio (alumina) e 45% de res\u00edduos s\u00f3lidos.<\/b><\/span><\/span><\/span><\/p>\n

a) <\/b><\/span><\/span><\/span>Considerando que em 2010 o Brasil produziu 32.10<\/b><\/span><\/span><\/span>6<\/b><\/span><\/span><\/sup><\/span>\u00a0toneladas de alum\u00ednio met\u00e1lico a partir da bauxita, calcule quantas toneladas de res\u00edduos s\u00f3lidos foram geradas nesse per\u00edodo por essa atividade.<\/b><\/span><\/span><\/span><\/p>\n

b) <\/b><\/span><\/span><\/span>Calcule o n\u00famero de banhos que poderiam ser tomados com a energia necess\u00e1ria para produzir apenas uma latinha de alum\u00ednio, estimando em 10 minutos o tempo de dura\u00e7\u00e3o do banho, em um chuveiro cuja pot\u00eancia \u00e9 de 3.000 W. Dado: W = J s<\/b><\/span><\/span><\/span>-1<\/b><\/span><\/span><\/sup><\/span>.<\/b><\/span><\/span><\/span><\/p>\n

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

54-(ENEM-MEC-012)<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

A efici\u00eancia das l\u00e2mpadas pode ser comparada utilizando a raz\u00e3o, considerada linear, entre a quantidade de luz produzida e o consumo. A quantidade de luz \u00e9 medida pelo fluxo luminoso, cuja unidade \u00e9 o l\u00famen(Im).<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

O consumo est\u00e1 relacionado \u00e0 pot\u00eancia el\u00e9trica da l\u00e2mpada que \u00e9 medida em watt(W). Por exemplo, uma l\u00e2mpada incandescente de 40 W emite cerca de 600 Im, enquanto uma l\u00e2mpada fluorescente de 40 W emite cerca de 3000 Im.<\/b><\/span><\/span><\/span><\/p>\n

Dispon\u00edvel em: http:\/\/tecnologia.terra.com.br.Acesso em :29 fev.2012(adaptado)<\/b><\/span><\/span><\/span><\/p>\n

A efici\u00eancia de uma l\u00e2mpada incandescente de 40 W \u00e9
\na) maior que a de uma l\u00e2mpada fluorescente de 8W,
\nb) maior que a de uma l\u00e2mpada fluorescente de 40 W, que produz menor quantidade de luz.
\nc) menor que a de uma l\u00e2mpada fluorescente de 8 W,que produz a mesma quantidade de luz.
\nd) menor que a de uma l\u00e2mpada fluorescente de 40 W, pois maior quantidade de energia.
\ne) igual a de uma l\u00e2mpada fluorescente de 40 W, que consome a mesma quantidade de energia.<\/b><\/span><\/span><\/span><\/p>\n

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

Resistores \u2013 Primeira lei de Ohm \u2013 Pot\u00eancia el\u00e9trica em um resistor<\/b><\/span><\/span><\/span><\/p>\n

47-(UEAP-AP-013)<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Marque a op\u00e7\u00e3o em que o gr\u00e1fico representa a Lei de Ohm.<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

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

48-(UFPA-PA-013)<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

No rio Amazonas, um pescador inexperiente tenta capturar um poraqu\u00ea segurando a cabe\u00e7a do peixe <\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

com uma m\u00e3o e a cauda com a outra. O poraqu\u00ea \u00e9 um peixe el\u00e9trico, capaz de gerar, entre a cabe\u00e7a e a cauda, uma diferen\u00e7a de potencial de at\u00e9 1500 V. Para esta diferen\u00e7a de potencial, a resist\u00eancia el\u00e9trica do corpo humano, medida entre as duas m\u00e3os, \u00e9 de aproximadamente 1000 \u03a9. Em geral, 500 mA de corrente cont\u00ednua, passando pelo t\u00f3rax de uma pessoa, s\u00e3o suficientes para provocar fibrila\u00e7\u00e3o ventricular e morte por parada cardiorrespirat\u00f3ria. Usando os valores mencionados acima, calculamos que a corrente que passa pelo t\u00f3rax do pescador, com rela\u00e7\u00e3o \u00e0 corrente suficiente para provocar fibrila\u00e7\u00e3o ventricular, \u00e9:<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

49-(UFRN-RN-013)<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Conhecido como um dos equipamentos que mais consome energia em uma resid\u00eancia, o chuveiro el\u00e9trico est\u00e1 presente na maioria dos lares brasileiros. Um chuveiro el\u00e9trico simples \u00e9 composto por uma c\u00e2mara, na qual existem dois resistores de dimens\u00f5es diferentes, como mostrado na figura abaixo. Existe ainda uma chave seletora que<\/b><\/span><\/span><\/span><\/p>\n

pode ser ligada na posi\u00e7\u00e3o VER\u00c3O ou na posi\u00e7\u00e3o INVERNO.<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Considere uma resid\u00eancia que consome\u00a0 em m\u00e9dia 200 kWh por m\u00eas, na qual est\u00e1 instalado um chuveiro cujas especifica\u00e7\u00f5es do fabricante s\u00e3o: 3.600\/4.800W, 220 V.<\/b><\/span><\/span><\/span><\/p>\n

A) <\/b><\/span><\/span><\/span>Em que posi\u00e7\u00e3o da figura acima, X ou Y, deve ser ligada a chave seletora do chuveiro para que ele opere no modo INVERNO (4.800 W)? Justifique sua resposta.<\/b><\/span><\/span><\/span><\/p>\n

B) <\/b><\/span><\/span><\/span>Determine o consumo de energia pelo chuveiro operando no modo INVERNO, durante um banho cuja dura\u00e7\u00e3o \u00e9 de 10 minutos.<\/b><\/span><\/span><\/span><\/p>\n

C) <\/b><\/span><\/span><\/span>Considerando que esse chuveiro est\u00e1 instalado em uma resid\u00eancia na qual moram quatro pessoas e que cada um\u00a0 toma um banho di\u00e1rio com dura\u00e7\u00e3o de 10 minutos, qual seria o percentual de economia em quilowatts na conta de energia da fam\u00edlia, se eles resolvessem deixar de usar o chuveiro el\u00e9trico? Justifique sua resposta.<\/b><\/span><\/span><\/span><\/p>\n

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

50-(PUC-MG-013)<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

O principal componente de um chuveiro el\u00e9trico \u00e9 a sua resist\u00eancia el\u00e9trica. Quando ela estraga, o <\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

equipamento deixa de aquecer a \u00e1gua. Sobre a capacidade do chuveiro de aquecer a \u00e1gua e sua resist\u00eancia el\u00e9trica, \u00e9 CORRETO afirmar:<\/b><\/span><\/span><\/span><\/p>\n

a) Se a resist\u00eancia do chuveiro for trocada por outra de maior valor, ele ir\u00e1 aquecer mais a \u00e1gua, fornecendo mais calor a ela.<\/b><\/span><\/span><\/span><\/p>\n

b) Quando fechamos um pouco a torneira, aumentamos a pot\u00eancia do chuveiro e a \u00e1gua sai com temperatura mais elevada.<\/b><\/span><\/span><\/span><\/p>\n

c) Quando abrimos mais a torneira, diminu\u00edmos a pot\u00eancia do chuveiro fazendo com que a \u00e1gua saia com temperatura mais baixa.<\/b><\/span><\/span><\/span><\/p>\n

d) Se diminu\u00edmos a resist\u00eancia el\u00e9trica do chuveiro, aumentamos sua pot\u00eancia fazendo com que a \u00e1gua saia com uma maior temperatura.<\/b><\/span><\/span><\/span><\/p>\n

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

51-(PUC-RS-013)<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

\u00a0O gr\u00e1fico a seguir mostra o comportamento da corrente el\u00e9trica em fun\u00e7\u00e3o da diferen\u00e7a de potencial entre os extremos de um fio condutor.<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

<\/a>Analisando os dados mostrados no gr\u00e1fico, conclui-se que a resist\u00eancia el\u00e9trica e a pot\u00eancia dissipada nesse condutor quando percorrido por uma corrente el\u00e9trica de 1,50A s\u00e3o, respectivamente,<\/b><\/span><\/span><\/span><\/p>\n

A) 60\u03a9, 60W\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 <\/b><\/span><\/span><\/span><\/p>\n

B) 60\u03a9, 80W\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 <\/b><\/span><\/span><\/span><\/p>\n

C) 40\u03a9, 90W\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 <\/b><\/span><\/span><\/span><\/p>\n

D) 40\u03a9 ,120W\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 <\/b><\/span><\/span><\/span><\/p>\n

E) 20\u03a9, 150W<\/b><\/span><\/span><\/span><\/p>\n

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

52-(PUC-PR-013)<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

O fus\u00edvel \u00e9 um componente projetado com o intuito de proteger circuitos el\u00e9tricos, seja em um carro, em uma resid\u00eancia ou at\u00e9 mesmo em grandes ind\u00fastrias.<\/b><\/span><\/span><\/span><\/p>\n

Por\u00e9m seu uso vem sendo substitu\u00eddo por outro componente, o disjuntor, j\u00e1 que este raramente <\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

precisa ser trocado, bastando apenas ser religado em caso de problemas. Com base nessas informa\u00e7\u00f5es e em seus conhecimentos a respeito desses acess\u00f3rios dos circuitos el\u00e9tricos, \u00e9 CORRETO afirmar:<\/b><\/span><\/span><\/span><\/p>\n

A) O fus\u00edvel n\u00e3o conduz corrente el\u00e9trica, ao contr\u00e1rio do disjuntor.<\/b><\/span><\/span><\/span><\/p>\n

B) Somente o disjuntor \u00e9 condutor, por isso vem substituindo os fus\u00edveis.<\/b><\/span><\/span><\/span><\/p>\n

C) Os fus\u00edveis atuam como elementos de prote\u00e7\u00e3o ao circuito el\u00e9trico, por\u00e9m n\u00e3o podem evitar poss\u00edveis inc\u00eandios.<\/b><\/span><\/span><\/span><\/p>\n

D) Tanto o fus\u00edvel quanto o disjuntor s\u00e3o condutores que t\u00eam como fun\u00e7\u00e3o evitar as correntes el\u00e9tricas excessivas.<\/b><\/span><\/span><\/span><\/p>\n

E) Em condi\u00e7\u00f5es normais de funcionamento, isto \u00e9, quando a corrente ultrapassa o valor m\u00e1ximo admitido, a temperatura atingida pelo fus\u00edvel \u00e9 inferior ao seu ponto de fus\u00e3o.<\/b><\/span><\/span><\/span><\/p>\n

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

Segunda lei de Ohm (Resistividade)<\/b><\/span><\/span><\/span><\/p>\n

33-(UNCISAl-AL-013)<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Sabendo que uma corrente el\u00e9trica maior que 200 mA pode ser fatal a um ser humano se mantida por um intervalo de tempo da ordem de alguns ciclos card\u00edacos, calcule o valor da corrente el\u00e9trica estabelecida se uma diferen\u00e7a de<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

potencial el\u00e9trico de 270 V for aplicada entre as duas m\u00e3os de um adulto por um intervalo de tempo de 120 s e<\/b><\/span><\/span><\/span><\/p>\n

determine se esta corrente \u00e9 suficiente para mat\u00e1-lo.<\/b><\/span><\/span><\/span><\/p>\n

Considere que a menor dist\u00e2ncia percorrida pela corrente el\u00e9trica entre as duas m\u00e3os \u00e9 1,5 m, a resistividade el\u00e9trica<\/b><\/span><\/span><\/span><\/p>\n

m\u00e9dia do corpo humano \u00e9 1,8 \u03a9m, o trajeto da corrente apresenta sec\u00e7\u00e3o circular de \u00e1rea 30 cm<\/b><\/span><\/span><\/span>2<\/b><\/span><\/span><\/sup><\/span>\u00a0e a frequ\u00eancia<\/b><\/span><\/span><\/span><\/p>\n

card\u00edaca \u00e9 igual a 80 ciclos card\u00edacos por minuto.<\/b><\/span><\/span><\/span><\/p>\n

A) 133,3 A; n\u00e3o \u00e9 suficiente.\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) 3000 A; \u00e9 suficiente.\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) 300 mA; n\u00e3o \u00e9 suficiente.<\/b><\/span><\/span><\/span><\/p>\n

D) 600 mA; \u00e9 suficiente.\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) 300 mA; \u00e9 suficiente.<\/b><\/span><\/span><\/span><\/p>\n

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

34-(URCA-CE-013)<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Visando a copa do mundo de 2014, cabos de a\u00e7o com 2,0 cm<\/b><\/span><\/span><\/span>2<\/b><\/span><\/span><\/sup><\/span>\u00a0de se\u00e7\u00e3o reta e 300 km de <\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

comprimento s\u00e3o utilizados para concluir a reforma e amplia\u00e7\u00e3o do p\u00e1tio de aeronaves do terminal de passageiros do aeroporto Pinto Martins, em Fortaleza.<\/b><\/span><\/span><\/span><\/p>\n

Podemos ent\u00e3o afirmar que a resist\u00eancia el\u00e9trica de cada um desses cabos, em ohm, \u00e9 igual a?<\/b><\/span><\/span><\/span><\/p>\n

DADO: \u03c1<\/b><\/span><\/span><\/span>a\u00e7o<\/b><\/span><\/span><\/sub><\/span>\u00a0= 1,8.10<\/b><\/span><\/span><\/span>-9\u00a0<\/b><\/span><\/span><\/sup><\/span>\u03a9.m<\/b><\/span><\/span><\/span><\/p>\n

a) 2,4 \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0b) 2,5 \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0c) 2,6 \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0d) 2,7 \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0e) 2,8<\/b><\/span><\/span><\/span><\/p>\n

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

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

Resistor equivalente nas associa\u00e7\u00f5es s\u00e9rie, paralelo e mista \u2013 curto circuito<\/b><\/span><\/span><\/span><\/p>\n

49-(UERN-RN-PSV-013)<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Na figura est\u00e3o representadas duas associa\u00e7\u00f5es de resistores.<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Considere que, aplicando-se uma tens\u00e3o de 60 V nos seus terminais, a diferen\u00e7a entre as correntes totais que as percorrem seja igual a 9 A. Sendo assim, o valor de R e igual a<\/b><\/span><\/span><\/span><\/p>\n

A) 2 \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 B) 5 \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 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 D) 10 \u2126.<\/b><\/span><\/span><\/span><\/p>\n

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

50-(FGV-RJ-013)<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Quando duas resist\u00eancias el\u00e9tricas de valores \u00a0R<\/b><\/span><\/span><\/span>1<\/b><\/span><\/span><\/sub><\/span>\u00a0e \u00a0R<\/b><\/span><\/span><\/span>2<\/b><\/span><\/span><\/sub><\/span>\u00a0s\u00e3o dispostas em paralelo (figura abaixo), o valor da resist\u00eancia equivalente \u00e0s duas primeiras \u00e9 dado por R=R<\/b><\/span><\/span><\/span>1<\/b><\/span><\/span><\/sub><\/span>.R<\/b><\/span><\/span><\/span>2<\/b><\/span><\/span><\/sub><\/span>\/(R<\/b><\/span><\/span><\/span>1<\/b><\/span><\/span><\/sub><\/span>\u00a0+ R<\/b><\/span><\/span><\/span>2<\/b><\/span><\/span><\/sub><\/span>)<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

A figura a seguir mostra duas semirretas AX e BY perpendiculares \u00e0 reta r. Na primeira foi marcado o ponto A’, de forma que AA\u2019=R<\/b><\/span><\/span><\/span>1<\/b><\/span><\/span><\/sub><\/span>\u00a0, e na segunda foi marcado o ponto B’, de forma que BB\u2019=R<\/b><\/span><\/span><\/span>2<\/b><\/span><\/span><\/sub><\/span>perpendicular a r. cortaram-se em P e foi tra\u00e7ado o segmento PP\u2019 \u00a0. As retas A\u2019B e\u00a0 AB\u2019<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Mostre que PP’ \u00e9 igual ao valor da resist\u00eancia R.<\/b><\/span><\/span><\/span><\/p>\n

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

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

Caracter\u00edsticas de associa\u00e7\u00e3o s\u00e9rie e associa\u00e7\u00e3o paralela<\/b><\/span><\/span><\/span><\/p>\n

60-(UERN-RN-PSV-013)<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Na figura est\u00e3o representadas duas associa\u00e7\u00f5es de resistores.<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Considere que, aplicando-se uma tens\u00e3o de 60 V nos seus terminais, a diferen\u00e7a entre as correntes totais que as percorrem seja igual a 9 A. Sendo assim, o valor de R e igual a<\/b><\/span><\/span><\/span><\/p>\n

A) 2 \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 B) 5 \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 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 D) 10 \u2126.<\/b><\/span><\/span><\/span><\/p>\n

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

61-(URCA-CE-013)<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Uma sala e iluminada por um circuito de l\u00e2mpadas incandescentes em paralelo. Considere os dados abaixo:<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

\u2212 a corrente el\u00e9trica eficaz limite do fus\u00edvel que protege esse circuito e igual a 10 A;<\/b><\/span><\/span><\/span><\/p>\n

\u2212 a tens\u00e3o eficaz dispon\u00edvel \u00e9 de 120 V;<\/b><\/span><\/span><\/span><\/p>\n

\u2212 sob essa tens\u00e3o, cada l\u00e2mpada consome uma potencia de 60 W.<\/b><\/span><\/span><\/span><\/p>\n

O numero m\u00e1ximo de l\u00e2mpadas que podem ser mantidas acesas corresponde a:<\/b><\/span><\/span><\/span><\/p>\n

a) 10\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 b) 15\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 c) 20\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 d) 25\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 e) 30<\/b><\/span><\/span><\/span><\/p>\n

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

62-(UNESP-SP-013)<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Determinada massa de \u00e1gua deve ser aquecida com o calor dissipado por uma associa\u00e7\u00e3o de resistores ligada nos pontos A e B do esquema mostrado na figura.<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Para isso, dois resistores \u00f4hmicos de mesma resist\u00eancia R podem ser associados e ligados aos pontos A e B. Uma ddp constante U, criada por um gerador ideal entre os pontos A e B, \u00e9 a mesma para ambas as associa\u00e7\u00f5es dos resistores, em s\u00e9rie ou em paralelo.<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Considere que todo calor dissipado pelos resistores seja absorvido pela \u00e1gua e que, se os resistores forem associados em s\u00e9rie, o aquecimento pretendido ser\u00e1 conseguido em 1 minuto.<\/b><\/span><\/span><\/span><\/p>\n

Dessa forma, se for utilizada a associa\u00e7\u00e3o em paralelo, o mesmo aquecimento ser\u00e1 conseguido num intervalo de tempo, em segundos, igual a<\/b><\/span><\/span><\/span><\/p>\n

(A) 30.\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 \u00a0\u00a0\u00a0\u00a0(B) 20.\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 (C) 10.\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 (D) 45.\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 (E) 15.<\/b><\/span><\/span><\/span><\/p>\n

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

63-(UNESP-SP-013)<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Em um jogo de perguntas e respostas, em que cada jogador deve responder quatro perguntas (P<\/b><\/span><\/span><\/span>1<\/b><\/span><\/span><\/sub><\/span>, P<\/b><\/span><\/span><\/span>2<\/b><\/span><\/span><\/sub><\/span>, P<\/b><\/span><\/span><\/span>3<\/b><\/span><\/span><\/sub><\/span>\u00a0e P<\/b><\/span><\/span><\/span>4<\/b><\/span><\/span><\/sub><\/span>), os acertos de cada participante s\u00e3o indicados por um painel luminoso constitu\u00eddo por quatro l\u00e2mpadas coloridas. Se uma pergunta for respondida corretamente, a l\u00e2mpada associada a ela acende. Se for respondida de forma errada, a l\u00e2mpada permanece apagada. A figura abaixo representa, de forma esquem\u00e1tica, o circuito que controla o painel. Se uma pergunta \u00e9 respondida corretamente, a chave numerada \u00a0associada a ela \u00e9 fechada, e a l\u00e2mpada correspondente acende no painel, indicando o acerto. Se as quatro perguntas forem respondidas erradamente, a chave C ser\u00e1 fechada no final, e o jogador totalizar\u00e1 zero pontos.<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Cada l\u00e2mpada tem resist\u00eancia el\u00e9trica constante de 60 \u2126 e, junto com as chaves, est\u00e3o conectadas ao ramo AB do circuito, mostrado na figura, onde est\u00e3o ligados um resistor \u00f4hmico de resist\u00eancia R = 20 \u2126, um gerador ideal de f.e.m. E = 120 V e um amper\u00edmetro A de resist\u00eancia desprez\u00edvel, que monitora a corrente no circuito. Todas as chaves e fios de liga\u00e7\u00e3o t\u00eam resist\u00eancias desprez\u00edveis.<\/b><\/span><\/span><\/span><\/p>\n

Calcule as indica\u00e7\u00f5es do amper\u00edmetro quando um participante for eliminado com zero acertos, e quando um participante errar apenas a P<\/b><\/span><\/span><\/span>2<\/b><\/span><\/span><\/sub><\/span><\/p>\n

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

64-(MACKENZIE-SP-013)<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Nesta \u00e9poca de Natal, muitas pessoas utilizam conjuntos de pequenas l\u00e2mpadas incandescentes, popularmente conhecidos por pisca-piscas, para adornarem ambientes. Um dos modelos utilizados por certa pessoa possui 4 s\u00e9ries de<\/b><\/span><\/span><\/span><\/p>\n

25 l\u00e2mpadas cada uma, que s\u00e3o associadas em paralelo entre si, conforme esquema abaixo:<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Considerando-se que os valores nominais do fabricante, da pot\u00eancia total e da tens\u00e3o el\u00e9trica entre os terminais A e B do pisca-pisca, s\u00e3o, respectivamente, 22 W e 220 V, a resist\u00eancia el\u00e9trica de cada l\u00e2mpada \u00e9<\/b><\/span><\/span><\/span><\/p>\n

a) 88 W\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 b) 176 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 c) 352 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 d) 460 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 e) 528 W<\/b><\/span><\/span><\/span><\/p>\n

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

65-(UNIFESP-SP-013)<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Observe a charge.<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Em uma \u00fanica tomada de tens\u00e3o nominal de 110 V, est\u00e3o ligados, por meio de um adaptador, dois abajures (com l\u00e2mpadas incandescentes com indica\u00e7\u00f5es comerciais de 40 W \u2013 110 V), um r\u00e1dio-rel\u00f3gio (com pot\u00eancia nominal de 20 W em 110 V) e um computador, com consumo de 120 W em 110 V. Todos os aparelhos el\u00e9tricos est\u00e3o em pleno funcionamento.<\/b><\/span><\/span><\/span><\/p>\n

a) Utilizando a representa\u00e7\u00e3o das resist\u00eancias \u00f4hmicas equivalentes de cada aparelho el\u00e9trico como R<\/b><\/span><\/span><\/span>L<\/b><\/span><\/span><\/sub><\/span>\u00a0para cada abajur, R<\/b><\/span><\/span><\/span>R<\/b><\/span><\/span><\/sub><\/span>\u00a0para o r\u00e1dio-rel\u00f3gio e R<\/b><\/span><\/span><\/span>C<\/b><\/span><\/span><\/sub><\/span>\u00a0para o computador, esboce o circuito el\u00e9trico que esquematiza a liga\u00e7\u00e3o desses 4 aparelhos el\u00e9tricos na tomada (adaptador) e, a partir dos dados da pot\u00eancia consumida por cada aparelho, calcule a corrente total no circuito, supondo que todos os cabos de liga\u00e7\u00e3o e o adaptador s\u00e3o ideais.<\/b><\/span><\/span><\/span><\/p>\n

b) Considerando que o valor aproximado a ser pago pelo consumo de 1,0 kWh \u00e9 R$ 0,30 e que os aparelhos permane\u00e7am ligados em m\u00e9dia 4 horas por dia durante os 30 dias do m\u00eas, calcule o valor a ser pago, no final de um m\u00eas de consumo, devido a estes aparelhos el\u00e9tricos.<\/b><\/span><\/span><\/span><\/p>\n

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

C\u00e1lculo de correntes, tens\u00f5es e pot\u00eancias em associa\u00e7\u00f5es mistas<\/b><\/span><\/span><\/span><\/p>\n

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

42-(UFPE-PE-013)<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

A figura mostra um circuito el\u00e9trico onde se aplica uma ddp de entrada e se mede uma ddp de sa\u00edda. Calcule qual deve<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

ser a raz\u00e3o R<\/b><\/span><\/span><\/span>1<\/b><\/span><\/span><\/sub><\/span>\/R<\/b><\/span><\/span><\/span>2<\/b><\/span><\/span><\/sub><\/span>, para que a ddp de sa\u00edda seja um d\u00e9cimo da ddp de entrada.<\/b><\/span><\/span><\/span><\/p>\n

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

43-(ESPCEX-013)<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Quatro l\u00e2mpadas \u00f4hmicas id\u00eanticas A, B, C e D foram associadas e, em seguida, a associa\u00e7\u00e3o \u00e9 ligada a um gerador de energia el\u00e9trica ideal. Em um dado instante, a l\u00e2mpada A queima, interrompendo o circuito no trecho em que ela se encontra. As l\u00e2mpadas B, C e D permanecem acesas, por\u00e9m o brilho da l\u00e2mpada B aumenta e o brilho das l\u00e2mpadas C e D diminui. Com base nesses dados, a alternativa que indica a associa\u00e7\u00e3o formada por essas l\u00e2mpadas \u00e9:<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

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

44-FUVEST-SP-013)<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

No circuito da figura ao lado, a diferen\u00e7a de potencial, em m\u00f3dulo, entre os pontos A e B \u00e9 de<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

a) 5 V. \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0b) 4 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\u00a0c) 3 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 d) 1 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 e) 0 V.<\/b><\/span><\/span><\/span><\/p>\n

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

Geradores\u00a0 – associa\u00e7\u00e3o de geradores<\/b><\/span><\/span><\/span><\/p>\n

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

48-(Cat\u00f3lica Santa Catarina \u2013SC-013)<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

O circuito a seguir \u00e9 composto de um gerador (\u03b5 = 12V e r = 1 \u03a9) e mais tr\u00eas resistores (R<\/b><\/span><\/span><\/span>1<\/b><\/span><\/span><\/sub><\/span>\u00a0= 7 \u03a9, R<\/b><\/span><\/span><\/span>2<\/b><\/span><\/span><\/sub><\/span>\u00a0= 3 \u03a9 e R<\/b><\/span><\/span><\/span>3<\/b><\/span><\/span><\/sub><\/span>\u00a0= 6 \u03a9).<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Qual \u00e9 o valor da diferen\u00e7a de potencial nos polos desse gerador?<\/b><\/span><\/span><\/span><\/p>\n

A) 12 volts.\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0B) 8,4 volts.\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 C) 10,8 volts.\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 D) 15 volts.\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 E) 11,2 volts.<\/b><\/span><\/span><\/span><\/p>\n

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

49-(CEFET-MG-013)<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Uma bateria cujas especifica\u00e7\u00f5es s\u00e3o 1,2 V e 1.200 mAh, ap\u00f3s ser completamente carregada, \u00e9 ligada <\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

a um motor de for\u00e7a contraeletromotriz de 1,0 V e resist\u00eancia interna 0,20 \u03a9.<\/b><\/span><\/span><\/span><\/p>\n

Considerando-se que essa bateria desenvolva toda sua pot\u00eancia nominal, o tempo, em horas, que ela consegue manter o motor em funcionamento, \u00e9<\/b><\/span><\/span><\/span><\/p>\n

a) 0,50.\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 b) 0,60.\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 c) 1,2.\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0d) 2,0.\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 e) 2,4<\/b><\/span><\/span><\/span><\/p>\n

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

50-(UFRN-RN-013)<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Em uma situa\u00e7\u00e3o em que a bateria de um carro est\u00e1\u00a0 descarregada e, portanto, n\u00e3o \u00e9 poss\u00edvel dar a partida no motor, geralmente uma bateria carregada \u00e9 ligada \u00e0 bateria do carro para faz\u00ea-lo funcionar.<\/b><\/span><\/span><\/span><\/p>\n

As figuras I e II abaixo representam duas alternativas para interligar as duas baterias atrav\u00e9s de fios condutores.<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

A figura que representa a liga\u00e7\u00e3o correta \u00e9 a<\/b><\/span><\/span><\/span><\/p>\n

A) II, cuja liga\u00e7\u00e3o \u00e9 do tipo em s\u00e9rie.\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) II, cuja liga\u00e7\u00e3o \u00e9 do tipo em paralelo.<\/b><\/span><\/span><\/span><\/p>\n

C) I, cuja liga\u00e7\u00e3o \u00e9 do tipo em s\u00e9rie.\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

D) I, cuja liga\u00e7\u00e3o \u00e9 do tipo em paralelo.<\/b><\/span><\/span><\/span><\/p>\n

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

51-(FUVEST-SP-013)<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Em uma aula de laborat\u00f3rio, os alunos determinaram a for\u00e7a eletromotriz \u03b5 e a resist\u00eancia interna r de uma bateria. Para realizar a tarefa, montaram o circuito representado na figura abaixo e, utilizando o volt\u00edmetro, mediram a diferen\u00e7a de<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

potencial V para diferentes valores da resist\u00eancia R do reostato. A partir dos resultados obtidos, calcularam a corrente I no reostato e constru\u00edram a tabela apresentada na p\u00e1gina de respostas.<\/b><\/span><\/span><\/span><\/p>\n

a) <\/b><\/span><\/span><\/span>Complete a tabela, na p\u00e1gina de respostas, com os valores da corrente I.<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

b) <\/b><\/span><\/span><\/span>Utilizando os eixos da p\u00e1gina de respostas, fa\u00e7a o gr\u00e1fico de V em fun\u00e7\u00e3o de I.<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

c) <\/b><\/span><\/span><\/span>Determine a for\u00e7a eletromotriz \u03b5 e a resist\u00eancia interna r da bateria.<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

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

Circuitos\u00a0 com geradores \u2013 exerc\u00edcios<\/b><\/span><\/span><\/span><\/p>\n

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

29-(PUC-RJ-013)<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Um determinado circuito \u00e9 composto de uma bateria de 12,0 V e mais quatro resistores, dispostos como mostra a figura.<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

a) <\/b><\/span><\/span><\/span>Determine a corrente el\u00e9trica no ponto A indicado na figura.<\/b><\/span><\/span><\/span><\/p>\n

b) <\/b><\/span><\/span><\/span>Determine a diferen\u00e7a de potencial entre os pontos B e C apresentados na figura.<\/b><\/span><\/span><\/span><\/p>\n

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

30-(PUC-RJ-013)<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

No circuito mostrado na figura, a diferen\u00e7a de potencial entre os pontos B e A vale, em Volts:<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

(A) 3,0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 (B) 1,0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 (C) 2,0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 (D) 4,5\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 (E) 0,75<\/b><\/span><\/span><\/span><\/p>\n

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

\u00a0<\/span>31-(MACKENZIE-SP-013)<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Um professor solicitou a um aluno que calculasse o valor da resist\u00eancia el\u00e9trica do resistor R representado ao lado, de maneira que a pot\u00eancia dissipada pelo resistor de 4 \u2126 fosse 36 W.<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

O estudante acertou a quest\u00e3o, pois sua resposta foi<\/b><\/span><\/span><\/span><\/p>\n

a) 2 \u2126\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 b) 4 \u2126\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 c) 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 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 e) 16 \u2126<\/b><\/span><\/span><\/span><\/p>\n

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

Receptores e associa\u00e7\u00e3o de geradores e de receptores \u2013 (lei de Pouillet)<\/b><\/span><\/span><\/span><\/p>\n

30-(UniFOA-RJ-013)<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Os receptores el\u00e9tricos s\u00e3o muito comuns no nosso dia a dia. Provavelmente voc\u00ea, que est\u00e1 lendo<\/b><\/span><\/span><\/span><\/p>\n

esse artigo, deve ter alguns deles na sua resid\u00eancia. Definem-se receptores el\u00e9tricos como qualquer<\/b><\/span><\/span><\/span><\/p>\n

dispositivo que transforma energia el\u00e9trica em energia n\u00e3o el\u00e9trica que n\u00e3o seja exclusivamente em<\/b><\/span><\/span><\/span><\/p>\n

energia t\u00e9rmica, pois os dispositivos que transformam e energia el\u00e9trica totalmente em energia t\u00e9rmica s\u00e3o definidos como resistores.<\/b><\/span><\/span><\/span><\/p>\n

(http:\/\/educacao.uol.com.br\/disciplinas\/fisica\/receptores-eletricos-ventiladores-liquidificadorese-batedeiras.htm)<\/b><\/span><\/span><\/span><\/p>\n

A ddp nos terminais de um grande ventilador de teto instalado em um hospital, varia com a corrente<\/b><\/span><\/span><\/span><\/p>\n

conforme o gr\u00e1fico abaixo.<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

\u00a0A resist\u00eancia interna e a fcem desse receptor el\u00e9trico s\u00e3o, respectivamente:<\/b><\/span><\/span><\/span><\/p>\n

a) 1 \u2126 e 37V\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 b) 2 \u2126 e 37V\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 c) 1 \u2126 e 40V\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 d) 3 \u2126 e 37V\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 e) 3 \u2126 e 40V<\/b><\/span><\/span><\/span><\/p>\n

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

31-(UFES-ES-013)<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

O circuito indicado ao lado \u00e9 composto de uma bateria n\u00e3o ideal e de uma carga resistiva (l\u00e2mpada L). <\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

O gr\u00e1fico representa a curva caracter\u00edstica tens\u00e3o U versus corrente I que a bateria fornece a diferentes cargas.<\/b><\/span><\/span><\/span><\/p>\n

Considere que a bateria esteja operando com uma particular l\u00e2mpada, \u00e0 qual fornece a particular corrente I = 6,0 A . Determine<\/b><\/span><\/span><\/span><\/p>\n

A) a for\u00e7a eletromotriz da bateria;<\/b><\/span><\/span><\/span><\/p>\n

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

C) a resist\u00eancia dessa particular l\u00e2mpada;<\/b><\/span><\/span><\/span><\/p>\n

D) a pot\u00eancia el\u00e9trica dissipada por essa l\u00e2mpada e o rendimento (efici\u00eancia) da bateria nessa situa\u00e7\u00e3o de<\/b><\/span><\/span><\/span><\/p>\n

opera\u00e7\u00e3o.<\/b><\/span><\/span><\/span><\/p>\n

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

Aparelhos de medi\u00e7\u00e3o el\u00e9trica (amper\u00edmetros, volt\u00edmetros, ponte de Wheatstone)<\/b><\/span><\/span><\/span><\/p>\n

36-(UFGD-MS-013)<\/b><\/span><\/span><\/span><\/p>\n

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

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

A figura a seguir corresponde a um painel composto por cinco l\u00e2mpadas id\u00eanticas.<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Supondo que o interruptor as conecte a uma bateria de 9 V, qual das l\u00e2mpadas n\u00e3o ir\u00e1 acender?<\/b><\/span><\/span><\/span><\/p>\n

(A) I. \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) II. \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(C) III. \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(D) IV. \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(E) V.<\/b><\/span><\/span><\/span><\/p>\n

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

\u00a0<\/span>37-(UEMA-MA-013)<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Um estudante de F\u00edsica, para verificar se um determinado condutor \u00e9 \u00f4hmico, usou uma fonte de tens\u00e3o C.C. vari\u00e1vel, um volt\u00edmetro, um amper\u00edmetro e fios de liga\u00e7\u00e3o. Ao ligar o circuito para diferentes tens\u00f5es, obteve os pares de valores, (U(v), i(A)), (U<\/b><\/span><\/span><\/span>1<\/b><\/span><\/span><\/sub><\/span>=1,50, i<\/b><\/span><\/span><\/span>1<\/b><\/span><\/span><\/sub><\/span>=0,04), (U<\/b><\/span><\/span><\/span>2<\/b><\/span><\/span><\/sub><\/span>=3,00, i<\/b><\/span><\/span><\/span>2<\/b><\/span><\/span><\/sub><\/span>=0,08), (U<\/b><\/span><\/span><\/span>3<\/b><\/span><\/span><\/sub><\/span>=4,50, i<\/b><\/span><\/span><\/span>3<\/b><\/span><\/span><\/sub><\/span>=0,13), (U<\/b><\/span><\/span><\/span>4<\/b><\/span><\/span><\/sub><\/span>=6,00, i<\/b><\/span><\/span><\/span>4<\/b><\/span><\/span><\/sub><\/span>=0,16), (U<\/b><\/span><\/span><\/span>5<\/b><\/span><\/span><\/sub><\/span>=7,50, i<\/b><\/span><\/span><\/span>5<\/b><\/span><\/span><\/sub><\/span>=0,21), (U<\/b><\/span><\/span><\/span>6<\/b><\/span><\/span><\/sub><\/span>=9,00, i<\/b><\/span><\/span><\/span>6<\/b><\/span><\/span><\/sub><\/span>=0,25) e (U<\/b><\/span><\/span><\/span>7<\/b><\/span><\/span><\/sub><\/span>=12,00, i<\/b><\/span><\/span><\/span>7<\/b><\/span><\/span><\/sub><\/span>=0,32).<\/b><\/span><\/span><\/span><\/p>\n

Nessas condi\u00e7\u00f5es, pode-se concluir, em rela\u00e7\u00e3o aos tr\u00eas aparelhos, que<\/b><\/span><\/span><\/span><\/p>\n

A) o amper\u00edmetro foi ligado em paralelo com o condutor, e o volt\u00edmetro foi ligado em s\u00e9rie com a fonte. O condutor n\u00e3o \u00e9 \u00f4hmico.<\/b><\/span><\/span><\/span><\/p>\n

B) o volt\u00edmetro foi ligado em s\u00e9rie com o condutor, e o amper\u00edmetro foi ligado em paralelo com a fonte. O condutor n\u00e3o \u00e9 \u00f4hmico.<\/b><\/span><\/span><\/span><\/p>\n

C) o volt\u00edmetro foi ligado em paralelo com o condutor, e o amper\u00edmetro foi ligado em s\u00e9rie com a fonte. O condutor \u00e9 \u00f4hmico.<\/b><\/span><\/span><\/span><\/p>\n

D) o volt\u00edmetro foi ligado em paralelo com o condutor, e o amper\u00edmetro foi ligado em s\u00e9rie com a fonte. O condutor n\u00e3o \u00e9 \u00f4hmico.<\/b><\/span><\/span><\/span><\/p>\n

E) o amper\u00edmetro foi ligado em paralelo com o condutor, e o volt\u00edmetro foi ligado em s\u00e9rie com a fonte. O condutor \u00e9 \u00f4hmico<\/b><\/span><\/span><\/span><\/p>\n

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

38-(ESPCEX-013)<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

O amper\u00edmetro \u00e9 um instrumento utilizado para a medida de intensidade de corrente el\u00e9trica em um circuito<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

constitu\u00eddo por geradores, receptores, resistores, etc. A maneira correta de conectar um amper\u00edmetro a um trecho do circuito no qual queremos determinar a intensidade da corrente \u00e9<\/b><\/span><\/span><\/span><\/p>\n

a)\u00a0 em s\u00e9rie \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/b><\/span><\/span><\/span><\/p>\n

b) em paralelo \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)\u00a0 na perpendicular \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/b><\/span><\/span><\/span><\/p>\n

d)\u00a0 em equivalente \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)\u00a0 mista<\/b><\/span><\/span><\/span><\/p>\n

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

Capacitores – condensadores<\/b><\/span><\/span><\/span><\/p>\n

52-(UERN-RN-PSV-013)<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

O capacitor equivalente de uma associa\u00e7\u00e3o em s\u00e9rie, constitu\u00edda por 3 capacitores iguais, tem capacit\u00e2ncia 2 pF.<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Utilizando-se 2 destes capacitores para montar uma associa\u00e7\u00e3o em paralelo, a mesma apresentar\u00e1 uma capacit\u00e2ncia de<\/b><\/span><\/span><\/span><\/p>\n

A) 3 pF.\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 \u00a0B) 6 pF. \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0C) 12 pF.\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 \u00a0D) 18 pF.<\/b><\/span><\/span><\/span><\/span><\/p>\n

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

53-(UFT-TO-013)<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Determinar, respectivamente, a capacit\u00e2ncia equivalente entre os terminais A e B e, tamb\u00e9m, a <\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

energia acumulada entre esses terminais quando o circuito est\u00e1 submetido a uma diferen\u00e7a de potencial constante de 500 V.<\/b><\/span><\/span><\/span><\/p>\n

(A) 100 \u03bcF; 50 J\u00a0\u00a0\u00a0\u00a0 <\/b><\/span><\/span><\/span><\/p>\n

(B) 65 \u03bcF; 8,125 J\u00a0\u00a0\u00a0\u00a0 <\/b><\/span><\/span><\/span><\/p>\n

(C) 50 \u03bcF; 8,125 J\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 <\/b><\/span><\/span><\/span><\/p>\n

(D) 200 \u03bcF; 60 J\u00a0\u00a0\u00a0\u00a0\u00a0 <\/b><\/span><\/span><\/span><\/p>\n

(E) 80 \u03bcF; 20 J<\/b><\/span><\/span><\/span><\/p>\n

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

54-(UniFOA-RJ-013)<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

O que realmente salva vidas em casos de parada cardiorrespirat\u00f3ria \u00e9 o choque el\u00e9trico no cora\u00e7\u00e3o (desfibrila\u00e7\u00e3o), o que pode ser feito por meio de um desfibrilador externo autom\u00e1tico, sendo que nem <\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

todos os casos de parada cardiorrespirat\u00f3ria t\u00eam indica\u00e7\u00e3o de choque el\u00e9trico.<\/b><\/span><\/span><\/span><\/p>\n

(www.cardiologiasemfronteiras.com.br\/2011\/07\/como-usar-o-desfibrilador-externo.html)<\/b><\/span><\/span><\/span><\/p>\n

Um aparelho moderno de desfibrila\u00e7\u00e3o possui um circuito an\u00e1logo ao descrito na figura abaixo.<\/b><\/span><\/span><\/span><\/p>\n

\"Eletrodin\u00e2mica\"<\/p>\n

Encontre a carga armazenada nesse desfibrilador sabendo que a tens\u00e3o sobre a qual ser\u00e1 ligado ser\u00e1 de 110V entre A e B e os capacit\u00e2ncias s\u00e3o determinadas por: C<\/b><\/span><\/span><\/span>1<\/b><\/span><\/span><\/sub><\/span>=20\u03bcF; C<\/b><\/span><\/span><\/span>2<\/b><\/span><\/span><\/sub><\/span>=30\u03bcF; C<\/b><\/span><\/span><\/span>3<\/b><\/span><\/span><\/sub><\/span>=10\u03bcF; C<\/b><\/span><\/span><\/span>4<\/b><\/span><\/span><\/sub><\/span>=40\u03bcF; C<\/b><\/span><\/span><\/span>5<\/b><\/span><\/span><\/sub><\/span>=50\u03bcF e C<\/b><\/span><\/span><\/span>6<\/b><\/span><\/span><\/sub><\/span>=60\u03bcF.<\/b><\/span><\/span><\/span><\/p>\n

a) 210\u03bcC\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 b) 4.200\u03bcC\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 c) 16,2\u03bcC\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 d) 12\u03bcC\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 e) 38\u03bcC<\/b><\/span><\/span><\/span><\/p>\n

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

Confira as resolu\u00e7\u00f5es dos exerc\u00edcios<\/span><\/a><\/h3>\n

 <\/p>\n

Clique aqui para ver sobre o tema!<\/a><\/p>\n

Confira as v\u00eddeo aulas!<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"

Vestibulares Recentes Eletrodin\u00e2mica – 2014 \u2013 2013 01-(UNISINOS-RS-014) Uma l\u00e2mpada de lanterna\u00a0apresenta as\u00a0se\u00adguintes especifica\u00e7\u00f5es: 12V \u2013 24W. Ao aplicar-se\u00a06V \u00e0 l\u00e2mpada, a\u00a0corrente el\u00e9trica\u00a0que nela circula \u00e9 de ……………… A, e a\u00a0pot\u00eancia que dissipa\u00a0\u00e9 de ……………… W. As\u00a0lacunas s\u00e3o corretamente preenchidas, respec\u00adtivamente, por 02-(UNIFESP-SP-014) Para compor sua decora\u00e7\u00e3o de Natal, um comerciante decide construir uma estrela para pendurar na fachada de<\/p>\n","protected":false},"author":1,"featured_media":0,"parent":3299,"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-3308","page","type-page","status-publish","hentry"],"aioseo_notices":[],"_links":{"self":[{"href":"https:\/\/fisicaevestibular.com.br\/novo\/wp-json\/wp\/v2\/pages\/3308","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=3308"}],"version-history":[{"count":5,"href":"https:\/\/fisicaevestibular.com.br\/novo\/wp-json\/wp\/v2\/pages\/3308\/revisions"}],"predecessor-version":[{"id":9917,"href":"https:\/\/fisicaevestibular.com.br\/novo\/wp-json\/wp\/v2\/pages\/3308\/revisions\/9917"}],"up":[{"embeddable":true,"href":"https:\/\/fisicaevestibular.com.br\/novo\/wp-json\/wp\/v2\/pages\/3299"}],"wp:attachment":[{"href":"https:\/\/fisicaevestibular.com.br\/novo\/wp-json\/wp\/v2\/media?parent=3308"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}