{"id":3302,"date":"2017-10-01T13:31:47","date_gmt":"2017-10-01T13:31:47","guid":{"rendered":"http:\/\/fisicaevestibular.com.br\/novo\/?page_id=3302"},"modified":"2024-06-30T00:16:09","modified_gmt":"2024-06-30T00:16:09","slug":"eletrodinamica-2017-2016-2015","status":"publish","type":"page","link":"https:\/\/fisicaevestibular.com.br\/novo\/vestibulares-recentes\/eletricidade\/eletrodinamica-2017-2016-2015\/","title":{"rendered":"Eletrodin\u00e2mica – 2017 \u2013 2016 – 2015"},"content":{"rendered":"

Vestibulares Recentes<\/span><\/span><\/span><\/h2>\n

Eletrodin\u00e2mica – 2017 \u2013 2016 – 2015<\/span><\/span><\/span><\/p>\n

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

01-UNICAMP-SP-017)<\/b><\/span><\/span><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Tecnologias m\u00f3veis como celulares e\u00a0<\/b><\/span><\/span>tablets<\/b><\/i><\/span><\/span>\u00a0<\/b><\/i><\/span><\/span>t\u00eam\u00a0<\/b><\/span><\/span>tempo<\/b><\/span><\/span>\u00a0de\u00a0<\/b><\/span><\/span>autonomia limitado<\/b><\/span><\/span>\u00a0pela\u00a0<\/b><\/span><\/span>carga armazenada\u00a0<\/b><\/span><\/span>em suas\u00a0<\/b><\/span><\/span>baterias.<\/b><\/span><\/span><\/span><\/span><\/p>\n

O\u00a0<\/b><\/span><\/span>gr\u00e1fico abaixo<\/b><\/span><\/span>\u00a0apresenta, de\u00a0<\/b><\/span><\/span>forma simplificada,<\/b><\/span><\/span>\u00a0a\u00a0<\/b><\/span><\/span>corrente de recarga <\/b><\/span><\/span>de uma\u00a0<\/b><\/span><\/span>c\u00e9lula de bateria<\/b><\/span><\/span>\u00a0de<\/b><\/span><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

\u00edon de l\u00edtio, em fun\u00e7\u00e3o do tempo.<\/b><\/span><\/span><\/span><\/span><\/p>\n

Considere uma\u00a0<\/b><\/span><\/span>c\u00e9lula de bateria inicialmente descarregada<\/b><\/span><\/span>\u00a0e que\u00a0<\/b><\/span><\/span>\u00e9 carregada seguindo essa curva de corrente.<\/b><\/span><\/span><\/span><\/span><\/p>\n

A sua\u00a0<\/b><\/span><\/span>carga no final da recarga<\/b><\/span><\/span>\u00a0\u00e9 de<\/b><\/span><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

02-(FMJ-SP-017)<\/b><\/span><\/span><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

O gr\u00e1fico representa, de forma simplificada, a\u00a0<\/b><\/span><\/span>intensidade da corrente el\u00e9trica, em fun\u00e7\u00e3o do tempo<\/b><\/span><\/span>, resultante do fluxo de \u00edons de s\u00f3dio atrav\u00e9s da membrana de um ax\u00f4nio gigante de lula, obtido em um experimento.<\/b><\/span><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

(www.sisne.org. Adaptado.)<\/b><\/span><\/span><\/span><\/span><\/p>\n

Considerando o valor da\u00a0<\/b><\/span><\/span>carga el\u00e9trica de cada \u00edon igual a 1,6.10-19\u00a0C<\/b><\/span><\/span>, a <\/b><\/span><\/span>quantidade de \u00edons de s\u00f3dio que atravessaram a membrana\u00a0<\/b><\/span><\/span>entre os instantes\u00a0<\/b><\/span><\/span>0 s e 4,0.10-3\u00a0s foi de<\/b><\/span><\/span><\/span><\/span><\/p>\n

(A) 2,5 \u00d7 10<\/b><\/span><\/span>3<\/b><\/span><\/sup><\/span>.<\/b><\/span><\/span><\/span><\/span><\/p>\n

(B) 5,0 \u00d7 10<\/b><\/span><\/span>3<\/b><\/span><\/sup><\/span>.<\/b><\/span><\/span><\/span><\/span><\/p>\n

(C) 7,5 \u00d7 10<\/b><\/span><\/span>4<\/b><\/span><\/sup><\/span>.<\/b><\/span><\/span><\/span><\/span><\/p>\n

(D) 2,5 \u00d7 10<\/b><\/span><\/span>5<\/b><\/span><\/sup><\/span>.<\/b><\/span><\/span><\/span><\/span><\/p>\n

(E) 5,0 \u00d7 10<\/b><\/span><\/span>5<\/b><\/span><\/sup><\/span>.<\/b><\/span><\/span><\/span><\/span><\/p>\n

 <\/p>\n

03-(FUVEST-SP-017)<\/b><\/span><\/span><\/span><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

\"\"<\/p>\n

a)<\/b><\/span><\/span>\u00a0zero\u00a0<\/b><\/span><\/span>e<\/b><\/span><\/span>\u00a0zero.<\/b><\/span><\/span><\/span><\/span><\/p>\n

b)<\/b><\/span><\/span>\u00a0zero\u00a0<\/b><\/span><\/span>e<\/b><\/span><\/span>\u00a0\u2013 5,0.10<\/b><\/span><\/span>-12<\/b><\/span><\/span>\u00a0C.<\/b><\/span><\/span><\/span><\/span><\/p>\n

c)<\/b><\/span><\/span>\u00a0\u2013 2,5.10<\/b><\/span><\/span>-12<\/b><\/span><\/span>\u00a0C\u00a0<\/b><\/span><\/span>e<\/b><\/span><\/span>\u00a0\u2013 2,5.10<\/b><\/span><\/span>-12<\/b><\/span><\/span>\u00a0C.<\/b><\/span><\/span><\/span><\/span><\/p>\n

d)<\/b><\/span><\/span>\u00a0\u2013 2,5.10<\/b><\/span><\/span>-12<\/b><\/span><\/span>\u00a0C\u00a0<\/b><\/span><\/span>e<\/b><\/span><\/span>\u00a0+ 2,5.10<\/b><\/span><\/span>-12\u00a0<\/b><\/span><\/span>C.<\/b><\/span><\/span><\/span><\/span><\/p>\n

e)<\/b><\/span><\/span>\u00a0+ 5,0.10<\/b><\/span><\/span>-12<\/b><\/span><\/span>\u00a0C\u00a0<\/b><\/span><\/span>e<\/b><\/span><\/span>\u00a0zero.<\/b><\/span><\/span><\/span><\/span><\/p>\n


\n<\/b><\/span><\/span>04-(UEL-PR-015)<\/b><\/span><\/span><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Desde a elabora\u00e7\u00e3o dos\u00a0<\/b><\/span><\/span><\/span>modelos at\u00f4micos<\/b><\/span><\/span><\/span>\u00a0por\u00a0<\/b><\/span><\/span><\/span>Dalton, Thomson, Rutherford e Bohr<\/b><\/span><\/span><\/span>, cientistas como\u00a0<\/b><\/span><\/span><\/span>Murray Gell-Man (EUA) e Georg Zweig (Alemanha<\/b><\/span><\/span><\/span>) t\u00eam desvendado os\u00a0<\/b><\/span><\/span><\/span>segredos subat\u00f4micos<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

da mat\u00e9ria.<\/b><\/span><\/span><\/span><\/p>\n

Assinale a\u00a0<\/b><\/span><\/span><\/span>alternativa que apresenta,\u00a0<\/b><\/span><\/span><\/span>corretamente, as subpart\u00edculas\u00a0<\/b><\/span><\/span><\/span>que constituem as\u00a0<\/b><\/span><\/span><\/span>part\u00edculas at\u00f4micas<\/b><\/span><\/span><\/span>\u00a0conforme os modelos de\u00a0<\/b><\/span><\/span><\/span>Gell-Man e Georg Zweig.<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

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

05-(UERJ-RJ-016)<\/b><\/span><\/span><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

\"\"<\/p>\n

06-(Faculdade Israelita de Ci\u00eancias da Sa\u00fade Albert Einstein \u2013 SP \u2013 016)<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

A descoberta se inscreve no \u201cesp\u00edrito Alfred Nobel\u201d de fazer\u00a0<\/b><\/span><\/span>inven\u00e7\u00f5es <\/b><\/span><\/span>que geram grandes\u00a0<\/b><\/span><\/span>benef\u00edcios \u00e0 humanidade<\/b><\/span><\/span>, afirmou o comit\u00ea do Nobel no instituto Karolinska, em Estocolmo, na Su\u00e9cia.<\/b><\/span><\/span><\/p>\n

No entanto, para\u00a0<\/b><\/span><\/span>obter a luz branca,<\/b><\/span><\/span>\u00a0era necess\u00e1rio ter a\u00a0<\/b><\/span><\/span>componente azul.<\/b><\/span><\/span>\u00a0A\u00a0<\/b><\/span><\/span>import\u00e2ncia\u00a0<\/b><\/span><\/span>vem do fato que era\u00a0<\/b><\/span><\/span>imposs\u00edvel obter l\u00e2mpadas com luz branca sem o uso do azul.<\/b><\/span><\/span><\/p>\n

Para fazer qualquer coisa, voc\u00ea\u00a0<\/b><\/span><\/span>precisa de tr\u00eas cores prim\u00e1rias (vermelho, verde e azul).<\/b><\/span><\/span><\/p>\n

Vermelho<\/b><\/span><\/span>\u00a0era mais f\u00e1cil por causa do\u00a0<\/b><\/span><\/span>arsenieto de g\u00e1<\/b><\/span><\/span>lio que j\u00e1 estava dispon\u00edvel, mas\u00a0<\/b><\/span><\/span>ningu\u00e9msabia como fazer o azul<\/b><\/span><\/span>, disse Nakamura em entrevista em 2009.<\/b><\/span><\/span><\/p>\n

Empolgado com a divulga\u00e7\u00e3o da not\u00edcia do pr\u00eamio Nobel de F\u00edsica de 2014, o SrPiril Lampo resolve\u00a0<\/b><\/span><\/span>desembolsar R$ 60,00 e substituir a l\u00e2mpada incandescente de sua casa, cuja pot\u00eancia \u00e9 de 100 W e cujo custo de aquisi\u00e7\u00e3o foi de R$ 5,00, por uma l\u00e2mpada de tecnologia LED, de 9 W, que tem o mesmo fluxo luminoso da l\u00e2mpada a ser substitu\u00edda.<\/b><\/span><\/span><\/p>\n

\"\"<\/p>\n

07-(Medicina \u2013 USCS-SP-016)<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

A\u00a0<\/b><\/span><\/span>pot\u00eancia nominal<\/b><\/span><\/span>\u00a0de consumo de um\u00a0<\/b><\/span><\/span>aparelho de<\/b><\/span><\/span>\u00a0<\/b><\/span><\/span>diagn\u00f3stico por imagem<\/b><\/span><\/span>\u00a0de certo hospital \u00e9 de\u00a0<\/b><\/span><\/span>2500 W<\/b><\/span><\/span>.<\/b><\/span><\/span><\/p>\n

\"\"<\/p>\n

Sabe-se<\/b><\/span><\/span>\u00a0que ele opera com\u00a0<\/b><\/span><\/span>rendimento de 90%,<\/b><\/span><\/span>\u00a0trabalhando\u00a0<\/b><\/span><\/span>durante 5 min de cada vez e 12 vezes a<\/b><\/span><\/span>\u00a0<\/b><\/span><\/span>cada dia, durante 20 dias \u00fateis por m\u00eas.<\/b><\/span><\/span><\/p>\n

Se o\u00a0<\/b><\/span><\/span>kWh custa R$ 0,90<\/b><\/span><\/span>, a\u00a0<\/b><\/span><\/span>despesa mensal de energia el\u00e9trica<\/b><\/span><\/span>\u00a0devido ao <\/b><\/span><\/span>uso<\/b><\/span><\/span>\u00a0desse\u00a0<\/b><\/span><\/span>aparelho<\/b><\/span><\/span>\u00a0\u00e9 de<\/b><\/span><\/span><\/p>\n

\"\"<\/p>\n

08-(MACKENZIE-SP-2017)<\/b><\/span><\/span><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

 <\/p>\n

Muitos\u00a0<\/b><\/span><\/span>aparelhos el\u00e9tricos s\u00e3o acionados por controle remoto.<\/b><\/span><\/span><\/span><\/span>\"\"<\/p>\n

O\u00a0<\/b><\/span><\/span>manual do usu\u00e1rio desses aparelhos<\/b><\/span><\/span>\u00a0informa que para\u00a0<\/b><\/span><\/span>mant\u00ea-lo em estado de prontid\u00e3o (stand-by), <\/b><\/span><\/span>isto \u00e9,\u00a0<\/b><\/span><\/span>acion\u00e1-lo por controle remoto, <\/b><\/span><\/span>\u00e9 necess\u00e1ria uma\u00a0<\/b><\/span><\/span>pot\u00eancia de 20 W.<\/b><\/span><\/span><\/span><\/span><\/p>\n

A\u00a0<\/b><\/span><\/span>energia consumida por esse aparelho em um dia\u00a0<\/b><\/span><\/span>\u00e9, aproximadamente,<\/b><\/span><\/span><\/span><\/span><\/p>\n

a)<\/b><\/span><\/span>\u00a01,3.10<\/b><\/span><\/span>6<\/b><\/span><\/sup><\/span>\u00a0J<\/b><\/span><\/span><\/span><\/span><\/p>\n

b)\u00a0<\/b><\/span><\/span>1,7.10<\/b><\/span><\/span>6<\/b><\/span><\/sup><\/span>\u00a0J\u00a0<\/b><\/span><\/span><\/span><\/span><\/p>\n

c)\u00a0<\/b><\/span><\/span>1,9.10<\/b><\/span><\/span>6<\/b><\/span><\/sup><\/span>\u00a0J\u00a0<\/b><\/span><\/span><\/span><\/span><\/p>\n

d)\u00a0<\/b><\/span><\/span>2,1.10<\/b><\/span><\/span>6<\/b><\/span><\/sup><\/span>\u00a0J<\/b><\/span><\/span><\/span><\/span><\/p>\n

e)\u00a0<\/b><\/span><\/span>2,3.10<\/b><\/span><\/span>6<\/b><\/span><\/sup><\/span>\u00a0J<\/b><\/span><\/span><\/span><\/span><\/p>\n

 <\/p>\n

09-(FGV-SP-017)<\/b><\/span><\/span><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

A\u00a0<\/b><\/span><\/span>usina hidrel\u00e9trica de Itaipu<\/b><\/span><\/span>, empresa\u00a0<\/b><\/span><\/span>binacional<\/b><\/span><\/span>, localizada na\u00a0<\/b><\/span><\/span>fronteira do Brasil com\u00a0<\/b><\/span><\/span>o\u00a0<\/b><\/span><\/span>Paraguai, tem uma pot\u00eancia instalada de 14 000 MW gerada por 20 unidades de 700 MW cada<\/b><\/span><\/span>.<\/b><\/span><\/span><\/span><\/span><\/p>\n

Essa\u00a0<\/b><\/span><\/span>pot\u00eancia \u00e9 distribu\u00edda por 12 linhas de transmiss\u00e3o<\/b><\/span><\/span>\u00a0que operam\u00a0<\/b><\/span><\/span>sob tens\u00e3o de 500 kV cada.<\/b><\/span><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

A\u00a0<\/b><\/span><\/span>energia produzida\u00a0<\/b><\/span><\/span>\u00e9 levada at\u00e9\u00a0<\/b><\/span><\/span>as cidades por cabos condutores de corrente el\u00e9trica,\u00a0<\/b><\/span><\/span>sustentados por\u00a0<\/b><\/span><\/span>altas torres que podem ser vistas quando se viaja pelas estradas.<\/b><\/span><\/span><\/span><\/span><\/p>\n

A\u00a0<\/b><\/span><\/span>intensidade da corrente el\u00e9trica atrav\u00e9s desses cabos \u00e9, em kA, mais pr\u00f3xima\u00a0<\/b><\/span><\/span>de<\/b><\/span><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

10-(FUVEST-SP-017)<\/b><\/span><\/span><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Na bateria\u00a0<\/b><\/span><\/span>de um telefone celular<\/b><\/span><\/span>\u00a0e em\u00a0<\/b><\/span><\/span>seu carregador,<\/b><\/span><\/span>\u00a0est\u00e3o registradas as\u00a0<\/b><\/span><\/span>seguintes especifica\u00e7\u00f5es:<\/b><\/span><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Com a\u00a0<\/b><\/span><\/span>bateria sendo carregada em uma rede de 127 V,<\/b><\/span><\/span>\u00a0a\u00a0<\/b><\/span><\/span>pot\u00eancia m\u00e1xima que o carregador pode<\/b><\/span><\/span>\u00a0<\/b><\/span><\/span>fornecer<\/b><\/span><\/span>\u00a0e a\u00a0<\/b><\/span><\/span>carga m\u00e1xima que pode ser armazenada na bateria<\/b><\/span><\/span>\u00a0s\u00e3o,\u00a0<\/b><\/span><\/span>respectivamente,<\/b><\/span><\/span>\u00a0pr\u00f3ximas de<\/b><\/span><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

\"\"<\/p>\n

11-(PUC-MG-015)<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Um\u00a0<\/b><\/span><\/span>chuveiro el\u00e9trico<\/b><\/span><\/span>\u00a0foi projetado para\u00a0<\/b><\/span><\/span>funcionar corretamente<\/b><\/span><\/span>\u00a0quando <\/b><\/span><\/span>ligado em 220<\/b><\/span><\/span>\u00a0<\/b><\/span><\/span>V<\/b><\/span><\/span><\/p>\n

\"\"<\/p>\n

Se ele\u00a0<\/b><\/span><\/span>for ligado<\/b><\/span><\/span>\u00a0a uma rede el\u00e9trica\u00a0<\/b><\/span><\/span>de 110 V<\/b><\/span><\/span>, \u00e9\u00a0<\/b><\/span><\/span>CORRETO\u00a0<\/b><\/span><\/span>afirmar que:<\/b><\/span><\/span><\/p>\n

a)<\/b><\/span><\/span>\u00a0sua resist\u00eancia el\u00e9trica ir\u00e1 reduzir pela metade fazendo com que ele aque\u00e7a menos a \u00e1gua.<\/b><\/span><\/span><\/p>\n

b)<\/b><\/span><\/span>\u00a0a resist\u00eancia do chuveiro ir\u00e1 se reduzir pela metade e sua pot\u00eancia n\u00e3o ser\u00e1 modificada.<\/b><\/span><\/span><\/p>\n

c)<\/b><\/span><\/span>\u00a0a resist\u00eancia do chuveiro ir\u00e1 dobrar de valor, j\u00e1 que a voltagem de 110 V \u00e9 a metade da voltagem de 220 V para a qual ele foi projetado.<\/b><\/span><\/span><\/p>\n

d)<\/b><\/span><\/span>\u00a0sua resist\u00eancia el\u00e9trica n\u00e3o muda de valor e sua pot\u00eancia ficar\u00e1 quatro vezes menor.<\/b><\/span><\/span><\/p>\n

12-(UEMG-MG-015)<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

\u201c<\/span>Nos an\u00fancios da tev\u00ea<\/b><\/span><\/span><\/p>\n

Somos lindos, sorridentes,<\/b><\/span><\/span><\/p>\n

Cabelos longos e radiosos\u2026\u201d<\/b><\/span><\/span><\/p>\n

(S\u00edsifo desce a montanha)<\/b><\/i><\/span><\/span><\/p>\n

Affonso<\/b><\/span><\/span>\u00a0chegou em casa,\u00a0<\/b><\/span><\/span>acendeu uma l\u00e2mpada, cuja pot\u00eancia \u00e9 de 60 W,<\/b><\/span><\/span>e, em seguida,\u00a0<\/b><\/span><\/span>ligou a<\/b><\/span><\/span><\/p>\n

\"\"<\/p>\n

televis\u00e3o, cuja pot\u00eancia \u00e9 de 90 W<\/b><\/span><\/span>. A\u00a0<\/b><\/span><\/span>l\u00e2mpada e a televis\u00e3o<\/b><\/span><\/span>\u00a0ficaram ligadas por\u00a0<\/b><\/span><\/span>uma (1) hora.<\/b><\/span><\/span><\/p>\n

Com rela\u00e7\u00e3o ao\u00a0<\/b><\/span><\/span>consumo de energia el\u00e9trica e \u00e0 tens\u00e3o el\u00e9trica nesse intervalo de tempo<\/b><\/span><\/span>, \u00e9\u00a0<\/b><\/span><\/span>CORRETO\u00a0<\/b><\/span><\/span>afirmar que<\/b><\/span><\/span><\/p>\n

A)<\/b><\/span><\/span>\u00a0o consumo da l\u00e2mpada \u00e9 maior, mas a tens\u00e3o nos dois aparelhos \u00e9 a mesma.<\/b><\/span><\/span><\/p>\n

B)<\/b><\/span><\/span>\u00a0tanto o consumo quanto a tens\u00e3o na televis\u00e3o s\u00e3o maiores.<\/b><\/span><\/span><\/p>\n

C)<\/b><\/span><\/span>\u00a0tanto o consumo quanto a tens\u00e3o na l\u00e2mpada s\u00e3o maiores.<\/b><\/span><\/span><\/p>\n

D)<\/b><\/span><\/span>\u00a0o consumo na televis\u00e3o \u00e9 maior, mas a tens\u00e3o nos dois aparelhos \u00e9 a mesma.<\/b><\/span><\/span><\/p>\n

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

13-(CEDERJ-RJ-015)<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

As\u00a0<\/b><\/span><\/span>extremidades<\/b><\/span><\/span>\u00a0de um\u00a0<\/b><\/span><\/span>peda\u00e7o de fio de comprimento L<\/b><\/span><\/span>\u00a0s\u00e3o conectadas aos terminais de uma <\/b><\/span><\/span>bateria ideal.<\/b><\/span><\/span>\u00a0Verifica-se que a\u00a0<\/b><\/span><\/span>corrente el\u00e9trica a qual percorre o fio \u00e9, nesse caso, i<\/b><\/span><\/span>1<\/b><\/span><\/sub><\/span>.<\/b><\/span><\/span>\u00a0O peda\u00e7o<\/b><\/span><\/span><\/p>\n

\"\"<\/p>\n

original \u00e9 substitu\u00eddo por outro, do\u00a0<\/b><\/span><\/span>mesmo fio,<\/b><\/span><\/span>\u00a0por\u00e9m com o\u00a0<\/b><\/span><\/span>dobro do comprimento<\/b><\/span><\/span>. Ap\u00f3s a substitui\u00e7\u00e3o, verifica-se que, sob a\u00a0<\/b><\/span><\/span>mesma voltagem, a corrente que o percorre \u00e9 i<\/b><\/span><\/span>2<\/b><\/span><\/sub><\/span>. Assinale<\/b><\/span><\/span><\/p>\n

a alternativa que descreve a\u00a0<\/b><\/span><\/span>rela\u00e7\u00e3o entre as correntes i<\/b><\/span><\/span>1<\/b><\/span><\/sub><\/span> e i<\/b><\/span><\/span>2<\/b><\/span><\/sub><\/span>.<\/b><\/span><\/span><\/p>\n

\"\"<\/p>\n

14-(UFRGS-RS-015)<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

No circuito esquematizado abaixo, R<\/b><\/span><\/span>1<\/b><\/span><\/sub><\/span> e R<\/b><\/span><\/span>2<\/b><\/span><\/sub><\/span> s\u00e3o resistores com a mesma resistividade \u03c1.<\/b><\/span><\/span><\/p>\n

\"\"<\/p>\n

R<\/b><\/span><\/span>1<\/b><\/span><\/sub><\/span> tem comprimento 2L e se\u00e7\u00e3o transversal A, e R<\/b><\/span><\/span>2<\/b><\/span><\/sub><\/span> tem comprimento L e se\u00e7\u00e3o transversal 2A.<\/b><\/span><\/span><\/p>\n

Nessa situa\u00e7\u00e3o, a corrente el\u00e9trica que percorre o circuito \u00e9<\/b><\/span><\/span><\/p>\n

(A) 2AV\/(5 \u03c1 L). <\/b><\/span><\/span><\/p>\n

(B) 2AV\/(3 \u03c1 L). <\/b><\/span><\/span><\/p>\n

(C) AV\/( \u03c1 L). <\/b><\/span><\/span><\/p>\n

(D) 3AV\/(2\u03c1 L). <\/b><\/span><\/span><\/p>\n

(E) 5AV\/(2 \u03c1 L).<\/b><\/span><\/span><\/p>\n

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

15-(UNIFESP-SP-016)<\/b><\/span><\/span><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Um\u00a0<\/b><\/span><\/span>fio met\u00e1lico homog\u00eaneo<\/b><\/span><\/span>\u00a0tem\u00a0<\/b><\/span><\/span>comprimento L<\/b><\/span><\/span>\u00a0<\/b><\/span>e \u00e1rea de sec\u00e7\u00e3o transversal constante.<\/b><\/span><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Com base no\u00a0<\/b><\/span><\/span>circuito representado na figura 2,<\/b><\/span><\/span>\u00a0calcule:<\/b><\/span><\/span><\/span><\/span><\/p>\n

a)<\/b><\/span><\/span>\u00a0a\u00a0<\/b><\/span><\/span>resist\u00eancia equivalente<\/b><\/span><\/span>, em\u00a0<\/b><\/span><\/span>\u03a9<\/b><\/span><\/span>.<\/b><\/span><\/span><\/span><\/span><\/p>\n

b)<\/b><\/span><\/span>\u00a0a\u00a0<\/b><\/span><\/span>pot\u00eancia total dissipada<\/b><\/span><\/span>, em\u00a0<\/b><\/span><\/span>W.<\/b><\/span><\/span><\/span><\/span><\/p>\n

 <\/p>\n

16-(ENEM-MEC-016)<\/b><\/span><\/span><\/span>
\n\"\"<\/b><\/span><\/span><\/span><\/span><\/span><\/p>\n

Por\u00a0<\/b><\/span><\/span>apresentar significativa resistividade el\u00e9trica<\/b><\/span><\/span>, o\u00a0<\/b><\/span><\/span>grafite<\/b><\/span><\/span>\u00a0pode ser utilizado para\u00a0<\/b><\/span><\/span>simular resistores el\u00e9tricos em circuitos desenhados no papel,<\/b><\/span><\/span>\u00a0com o uso de\u00a0<\/b><\/span><\/span>l\u00e1pis e lapiseiras.<\/b><\/span><\/span><\/span><\/span><\/p>\n

Dependendo da\u00a0<\/b><\/span><\/span>espessura e do comprimento das linhas desenhadas<\/b><\/span><\/span>, \u00e9 poss\u00edvel\u00a0<\/b><\/span><\/span>determinar\u00a0<\/b><\/span><\/span>a\u00a0<\/b><\/span><\/span>resist\u00eancia el\u00e9trica de cada tra\u00e7ado produzido.<\/b><\/span><\/span><\/span><\/span><\/p>\n

No\u00a0<\/b><\/span><\/span>esquema foram utilizados tr\u00eas tipos de l\u00e1pis diferentes (2H, HB e 6B)<\/b><\/span><\/span>para efetuar\u00a0<\/b><\/span><\/span>tr\u00eas tra\u00e7ados<\/b><\/span><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

distintos.<\/b><\/span><\/span><\/span><\/span><\/p>\n

Munida dessas informa\u00e7\u00f5es,<\/b><\/span><\/span>\u00a0um estudante\u00a0<\/b><\/span><\/span>pegou\u00a0<\/b><\/span><\/span>uma\u00a0<\/b><\/span><\/span>folha de papel<\/b><\/span><\/span>\u00a0e fez o\u00a0<\/b><\/span><\/span>desenho de um sorvete de casquinha utilizando-se desses tra\u00e7ados.<\/b><\/span><\/span><\/span><\/span><\/p>\n

Os\u00a0<\/b><\/span><\/span>valores\u00a0<\/b><\/span><\/span>encontrados nesse\u00a0<\/b><\/span><\/span>experimento,<\/b><\/span><\/span>\u00a0para as\u00a0<\/b><\/span><\/span>resist\u00eancias el\u00e9tricas (R),<\/b><\/span><\/span>\u00a0medidas com o\u00a0<\/b><\/span><\/span>aux\u00edlio de um ohm\u00edmetro ligado<\/b><\/span><\/span>\u00a0nas\u00a0<\/b><\/span><\/span>extremidades das resist\u00eancias, s\u00e3o mostrados na figura.<\/b><\/span><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Verificou-se<\/b><\/span><\/span>\u00a0que os\u00a0<\/b><\/span><\/span>resistores obedeciam a Lei de Ohm.<\/b><\/span><\/span><\/span><\/span><\/p>\n

Na\u00a0<\/b><\/span><\/span>sequ\u00eancia, conectou o ohm\u00edmetro nos terminais A e B<\/b><\/span><\/span>\u00a0do\u00a0<\/b><\/span><\/span>desenho<\/b><\/span><\/span>\u00a0e, em seguida,\u00a0<\/b><\/span><\/span>conectou-o nos terminais B e C,\u00a0<\/b><\/span><\/span>anotando as\u00a0<\/b><\/span><\/span>leituras R<\/b><\/span><\/span>AB<\/b><\/span><\/sub><\/span>\u00a0e R<\/b><\/span><\/span>BC<\/b><\/span><\/sub><\/span>, respectivamente.<\/b><\/span><\/span><\/span><\/span><\/p>\n

Ao\u00a0<\/b><\/span><\/span>estabelecer a raz\u00e3o R<\/b><\/span><\/span>AB<\/b><\/span><\/sub><\/span> \/ R<\/b><\/span><\/span>BC<\/b><\/span><\/sub><\/span> qual resultado o estudante obteve?<\/b><\/span><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

 <\/p>\n

17-(Faculdade Israelita de Ci\u00eancias da Sa\u00fade Albert Einstein \u2013 SP \u2013 016)<\/b><\/span><\/span><\/span><\/span><\/span><\/p>\n

Por decis\u00e3o da Assembleia Geral da Unesco, realizada em dezembro de 2013, a\u00a0<\/b><\/span><\/span>luz e as tecnologias<\/b><\/span><\/span>\u00a0nela baseadas ser\u00e3o celebradas ao longo de<\/b><\/span><\/span>2015<\/b><\/span><\/span>, que passar\u00e1 a ser referido simplesmente como\u00a0<\/b><\/span><\/span>Ano Internacional da Luz<\/b><\/span><\/span>. O trabalho de Albert Einstein sobre o efeito fotoel\u00e9trico (1905) foi fundamental para a ci\u00eancia e a tecnologia desenvolvidas a partir de 1950, incluindo a\u00a0<\/b><\/span><\/span>fot\u00f4nica,\u00a0<\/b><\/span><\/span>tida como a\u00a0<\/b><\/span><\/span>tecnologia do s\u00e9culo 21.<\/b><\/span><\/span><\/span><\/span><\/p>\n

Com o intuito de homenagear o c\u00e9lebre cientista, um eletricista elabora um\u00a0<\/b><\/span><\/span>inusitado aquecedor\u00a0<\/b><\/span><\/span>conforme mostra a figura abaixo.<\/b><\/span><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Esse\u00a0<\/b><\/span><\/span>aquecedor<\/b><\/span><\/span>\u00a0ser\u00e1 submetido a uma\u00a0<\/b><\/span><\/span>tens\u00e3o el\u00e9trica de 120V, entre seus terminais A e B,<\/b><\/span><\/span>\u00a0e ser\u00e1 utilizado,\u00a0<\/b><\/span><\/span>totalmente imerso, para aquecer a \u00e1gua que enche completamente um aqu\u00e1rio de dimens\u00f5es 30cm x 50cmx 80cm.<\/b><\/span><\/span><\/span><\/span><\/p>\n

Desprezando qualquer tipo de perda<\/b><\/span><\/span>, supondo\u00a0<\/b><\/span><\/span>constante a pot\u00eancia do aquecedor\u00a0<\/b><\/span><\/span>e considerando que a distribui\u00e7\u00e3o de calor para a \u00e1gua se d\u00ea de maneira uniforme,\u00a0<\/b><\/span><\/span>determine ap\u00f3s quantas horas\u00a0<\/b><\/span><\/span>de funcionamento, aproximadamente, ele ser\u00e1\u00a0<\/b><\/span><\/span>capaz de provocar uma varia\u00e7\u00e3o de temperatura de 36\u00b0F na \u00e1gua desse aqu\u00e1rio<\/b><\/span><\/span><\/span><\/span><\/p>\n

Adote:
\nPress\u00e3o atmosf\u00e9rica =<\/b><\/span><\/span>\u00a01 atm<\/b><\/span><\/span><\/span><\/span><\/p>\n

Densidade da \u00e1gua =\u00a0<\/b><\/span><\/span>1 g\/cm3<\/b><\/span><\/span><\/span><\/span><\/p>\n

Calor espec\u00edfico da \u00e1gua =\u00a0<\/b><\/span><\/span>1g.cm<\/b><\/span><\/span>-3<\/b><\/span><\/sup><\/span> .<\/b><\/span><\/span>o<\/b><\/span><\/sup><\/span>C<\/b><\/span><\/span>-1<\/b><\/span><\/sup><\/span><\/span><\/span><\/p>\n

Resist\u00eancia do resistor =<\/b><\/span><\/span>\u00a01 \u2126<\/b><\/span><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

 <\/p>\n

18-(UNIFESO-RJ-015)<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

No\u00a0<\/b><\/span><\/span>circuito\u00a0<\/b><\/span><\/span>esquematizado na figura, o\u00a0<\/b><\/span><\/span>gerador tem uma resist\u00eancia interna desprez\u00edvel<\/b><\/span><\/span>, os<\/b><\/span><\/span><\/p>\n

\"\"<\/p>\n

quatro resistores t\u00eam a mesma resist\u00eancia R<\/b><\/span><\/span>\u00a0e o\u00a0<\/b><\/span><\/span>amper\u00edmetro (ideal) indica 5 A<\/b><\/span><\/span>. Se a\u00a0<\/b><\/span><\/span>chave C estivesse fechada<\/b><\/span><\/span>, o\u00a0<\/b><\/span><\/span>amper\u00edmetro estaria indicando<\/b><\/span><\/span><\/p>\n

\"\"<\/p>\n

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

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

19-(ENEM-MEC-015)<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

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

 <\/p>\n

20-(UNICAMP-SP-016)<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Muitos\u00a0<\/b><\/span><\/span>dispositivos de aquecimento\u00a0<\/b><\/span><\/span>usados em nosso cotidiano usam<\/b><\/span><\/span>resistores el\u00e9tricos<\/b><\/span><\/span>\u00a0como\u00a0<\/b><\/span><\/span>fonte de calor.<\/b><\/span><\/span><\/p>\n

Um exemplo \u00e9 o\u00a0<\/b><\/span><\/span>chuveiro el\u00e9trico,<\/b><\/span><\/span>\u00a0em que \u00e9\u00a0<\/b><\/span><\/span>poss\u00edvel escolher entre diferentes op\u00e7\u00f5es de pot\u00eancias<\/b><\/span><\/span><\/p>\n

\"\"<\/p>\n

usadas no aquecimento da \u00e1gua, por exemplo, morno (M), quente (Q) e muito quente (MQ).<\/b><\/span><\/span><\/p>\n

Considere um\u00a0<\/b><\/span><\/span>chuveiro que usa a associa\u00e7\u00e3o de tr\u00eas resistores, iguais entre si<\/b><\/span><\/span>, para oferecer<\/b><\/span><\/span><\/p>\n

essas\u00a0<\/b><\/span><\/span>tr\u00eas op\u00e7\u00f5es de temperatura.<\/b><\/span><\/span><\/p>\n

A\u00a0<\/b><\/span><\/span>escolha \u00e9 feita por uma chave que liga a rede el\u00e9trica entre o ponto indicado pela letra N\u00a0<\/b><\/span><\/span>e um <\/b><\/span><\/span>outro ponto indicado por M, Q ou MQ, de acordo com a op\u00e7\u00e3o de temperatura desejada.<\/b><\/span><\/span>\u00a0O\u00a0<\/b><\/span><\/span>esquema\u00a0<\/b><\/span><\/span>que representa <\/b><\/span><\/span>corretamente o circuito equivalente do chuveiro<\/b><\/span><\/span>\u00a0\u00e9<\/b><\/span><\/span><\/p>\n

\"\"<\/p>\n

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

21-(FAMERP-SP-017)<\/b><\/span><\/span><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Uma\u00a0<\/b><\/span><\/span>l\u00e2mpada incandescente,\u00a0<\/b><\/span><\/span>de\u00a0<\/b><\/span><\/span>especifica\u00e7\u00f5es t\u00e9cnicas 40 V \u2013 25 W <\/b><\/span><\/span>estabelecidas pelo fabricante\u00a0<\/b><\/span><\/span>queima se for submetida a tens\u00f5es acima da especificada.<\/b><\/span><\/span><\/span><\/span><\/p>\n

Conforme a\u00a0<\/b><\/span><\/span>figura,\u00a0<\/b><\/span><\/span>essa\u00a0<\/b><\/span><\/span>l\u00e2mpada ser\u00e1 instalada em um soquete ligado em s\u00e9rie com o resistor R\u00a0<\/b><\/span><\/span>e\u00a0<\/b><\/span><\/span>com outros resistores que ser\u00e3o conectados entre os pontos A e B, formando um circuito que <\/b><\/span><\/span>Considerando que os\u00a0<\/b><\/span><\/span>fios e as conex\u00f5es utilizados nesse circuito tenham resist\u00eancias desprez\u00edveis: <\/b><\/span><\/span><\/span><\/span><\/p>\n

a)<\/b><\/span><\/span><\/span> determine <\/b><\/span><\/span>a <\/b><\/span><\/span>quantidade de carga el\u00e9trica, em coulombs,\u00a0<\/b><\/span><\/span>que atravessar\u00e1 a\u00a0<\/b><\/span><\/span>l\u00e2mpada\u00a0<\/b><\/span><\/span>se ela\u00a0<\/b><\/span><\/span>permanecer acesa, de acordo com suas especifica\u00e7\u00f5es, durante 20 minutos.<\/b><\/span><\/span><\/span><\/span><\/p>\n

b)<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span>indique o\u00a0<\/b><\/span><\/span>n\u00famero m\u00e1ximo de resistores iguais, de 320 \u03a9 cada um,\u00a0<\/b><\/span><\/span>que podem ser\u00a0<\/b><\/span><\/span>ligados em paralelo entre A e B, sem que a l\u00e2mpada queime.<\/b><\/span><\/span><\/span><\/span><\/p>\n

 <\/p>\n

22-(ENEM-MEC-016)<\/b><\/span><\/span><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

\"\"<\/p>\n

23-(UERJ-RJ-015)<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

No\u00a0<\/b><\/span><\/span>esquema abaixo<\/b><\/span><\/span>, est\u00e1 representada a instala\u00e7\u00e3o de uma\u00a0<\/b><\/span><\/span>torneira el\u00e9trica.<\/b><\/span><\/span><\/p>\n

\"\"<\/p>\n

De acordo com as\u00a0<\/b><\/span><\/span>informa\u00e7\u00f5es do fabricante<\/b><\/span><\/span>, a\u00a0<\/b><\/span><\/span>resist\u00eancia interna\u00a0<\/b><\/span><\/span>r\u00a0<\/b><\/span><\/span>da torneira corresponde a\u00a0<\/b><\/span><\/span>200 \u03a9.<\/b><\/span><\/span>\u00a0A\u00a0<\/b><\/span><\/span>corrente\u00a0<\/b><\/span><\/span>que deve percorrer o circuito da torneira \u00e9 de\u00a0<\/b><\/span><\/span>127 mA.<\/b><\/span><\/span><\/p>\n

Determine o\u00a0<\/b><\/span><\/span>valor da resist\u00eancia\u00a0<\/b><\/span><\/span>R\u00a0<\/b><\/span><\/span>que deve ser ligada\u00a0<\/b><\/span><\/span>em s\u00e9rie \u00e0 torneira <\/b><\/span><\/span>para que esta possa<\/b><\/span><\/span><\/p>\n

funcionar de acordo com a especifica\u00e7\u00e3o do fabricante, quando ligada a uma tomada de\u00a0<\/b><\/span><\/span>127 V.<\/b><\/span><\/span><\/p>\n

Calcule, em\u00a0<\/b><\/span><\/span>watts,<\/b><\/span><\/span>\u00a0a\u00a0<\/b><\/span><\/span>pot\u00eancia dissipada<\/b><\/span><\/span>\u00a0por essa torneira.<\/b><\/span><\/span><\/p>\n

 <\/p>\n

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

 <\/p>\n

24-(EsPCEx- AMAN \u2013 SP- RJ \u2013 2016\/17)<\/b><\/span><\/span><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Um\u00a0<\/b><\/span><\/span>aluno\u00a0<\/b><\/span><\/span>ir\u00e1\u00a0<\/b><\/span><\/span>montar um circuito el\u00e9trico\u00a0<\/b><\/span><\/span>com\u00a0<\/b><\/span><\/span>duas l\u00e2mpadas incandescentes, L<\/b><\/span><\/span>1<\/b><\/span><\/sub><\/span>\u00a0e L<\/b><\/span><\/span>2<\/b><\/span><\/sub><\/span>,\u00a0<\/b><\/span><\/span>de\u00a0<\/b><\/span><\/span>resist\u00eancias el\u00e9tricas constantes,<\/b><\/span><\/span>\u00a0que t\u00eam as seguintes\u00a0<\/b><\/span><\/span>especifica\u00e7\u00f5es t\u00e9cnicas fornecidas pelo fabricante,\u00a0<\/b><\/span><\/span>impressas nas l\u00e2mpadas:<\/b><\/span><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Al\u00e9m das duas l\u00e2mpadas,\u00a0<\/b><\/span><\/span>ele tamb\u00e9m usar\u00e1 um\u00a0<\/b><\/span><\/span>gerador ideal de tens\u00e3o el\u00e9trica cont\u00ednua de 60 V,\u00a0<\/b><\/span><\/span>um\u00a0<\/b><\/span><\/span>resistor \u00f4hmico de 30 \u2126\u00a0<\/b><\/span><\/span>e\u00a0<\/b><\/span><\/span>fios condutores el\u00e9tricos ideais.<\/b><\/span><\/span><\/span><\/span><\/p>\n

Utilizando\u00a0<\/b><\/span><\/span>todo material acima descrito,\u00a0<\/b><\/span><\/span>a\u00a0<\/b><\/span><\/span>configura\u00e7\u00e3o<\/b><\/span><\/span>\u00a0da\u00a0<\/b><\/span><\/span>montagem do circuito el\u00e9trico,<\/b><\/span><\/span>\u00a0para que as\u00a0<\/b><\/span><\/span>l\u00e2mpadas funcionem corretamente\u00a0<\/b><\/span><\/span>com os <\/b><\/span><\/span>valores especificados pelo fabricante das l\u00e2mpadas\u00a0<\/b><\/span><\/span>ser\u00e1:<\/b><\/span><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

\"\"<\/p>\n

 <\/p>\n

25-(Medicina \u2013 USCS-SP-017)<\/b><\/span><\/span><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

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

26-(UNIFESP-SP-017)<\/b><\/span><\/span><\/span><\/span><\/span><\/p>\n

\"\"A figura<\/b><\/span><\/span>\u00a0representa o\u00a0<\/b><\/span><\/span>esquema de uma panela el\u00e9trica,<\/b><\/span><\/span>\u00a0na qual\u00a0<\/b><\/span><\/span>existe uma chave seletora C\u00a0<\/b><\/span><\/span>que pode\u00a0<\/b><\/span><\/span>ser ligada em dois pontos, A e B<\/b><\/span><\/span>, que <\/b><\/span><\/span>definem qual circuito ser\u00e1 utilizado para dissipar,<\/b><\/span><\/span>\u00a0por\u00a0<\/b><\/span><\/span>efeito joule,<\/b><\/span><\/span>\u00a0a <\/b><\/span><\/span>energia t\u00e9rmica<\/b><\/span><\/span>\u00a0necess\u00e1ria para o\u00a0<\/b><\/span><\/span>funcionamento da panela.<\/b><\/span><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Uma\u00a0<\/b><\/span><\/span>pessoa<\/b><\/span><\/span>\u00a0deseja utilizar\u00a0<\/b><\/span><\/span>essa panela para elevar a temperatura de quatro litros de \u00e1gua de 20 \u00baC<\/b><\/span><\/span>\u00a0<\/b><\/span><\/span>para 80 \u00baC.<\/b><\/span><\/span><\/span><\/span><\/p>\n

Considerando que o\u00a0<\/b><\/span><\/span>calor espec\u00edfico da \u00e1gua seja 4.10<\/b><\/span><\/span>3<\/b><\/span><\/sup><\/span>\u00a0J\/(kg<\/b><\/span><\/span>\u22c5<\/b><\/span><\/span><\/span>\u00baC),<\/b><\/span><\/span>\u00a0que a densidade da\u00a0<\/b><\/span><\/span>\u00e1gua seja 1<\/b><\/span><\/span>\u00a0<\/b><\/span><\/span>kg\/L,<\/b><\/span><\/span>\u00a0que\u00a0<\/b><\/span><\/span>toda a energia t\u00e9rmica dissipada pelos resistores seja absorvida pela \u00e1gua\u00a0<\/b><\/span><\/span>e, ainda, que a\u00a0<\/b><\/span><\/span>\u00e1gua n\u00e3o perca calor durante o processo,<\/b><\/span><\/span>\u00a0calcule:<\/b><\/span><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Geradores, receptores e associa\u00e7\u00e3o de geradores e de receptores <\/span><\/span><\/span><\/p>\n

27-(EsPCEx-AMAN-SP-RJ)<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Em um\u00a0<\/b><\/span><\/span>circuito el\u00e9trico<\/b><\/span><\/span>, representado no desenho abaixo, o valor da\u00a0<\/b><\/span><\/span>for\u00e7a eletromotriz (fem)<\/b><\/span><\/span><\/p>\n

\"\"<\/p>\n

do gerador ideal \u00e9\u00a0<\/b><\/span><\/span>E=1,5 V<\/b><\/span><\/span>, e os valores das\u00a0<\/b><\/span><\/span>resist\u00eancias dos resistores <\/b><\/span><\/span>\u00f4hmicos s\u00e3o<\/b><\/span><\/span><\/p>\n

R1=R4=0,3 \u2126 , R2=R3=0,6 \u2126 e R5=0,15 \u2126\u00a0<\/b><\/span><\/span>. As\u00a0<\/b><\/span><\/span>leituras<\/b><\/span><\/span>\u00a0no\u00a0<\/b><\/span><\/span>volt\u00edmetro V e no amper\u00edmetro A<\/b><\/span><\/span>, ambos<\/b><\/span><\/span><\/p>\n

ideais<\/b><\/span><\/span>, s\u00e3o, respectivamente,<\/b><\/span><\/span><\/p>\n

[A]\u00a0<\/b><\/span><\/span>0,375 V e 2,50 A\u00a0<\/b><\/span><\/span><\/p>\n

[B]\u00a0<\/b><\/span><\/span>0,750 V e 1,00 A\u00a0<\/b><\/span><\/span><\/p>\n

[C]\u00a0<\/b><\/span><\/span>0,375 V e 1,25 A\u00a0<\/b><\/span><\/span><\/p>\n

[D]\u00a0<\/b><\/span><\/span>0,750 V e 1,25 A<\/b><\/span><\/span><\/p>\n

[E]\u00a0<\/b><\/span><\/span>0,750 V e 2,50 A<\/b><\/span><\/span><\/p>\n

28-(EsPCEx- AMAN \u2013 SP- RJ \u2013 2016\/17)<\/b><\/span><\/span><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

\"\"<\/p>\n

O\u00a0<\/b><\/span><\/span>desenho<\/b><\/span><\/span>\u00a0ao lado representa um\u00a0<\/b><\/span><\/span>circuito el\u00e9trico composto por resistores \u00f4hmicos,\u00a0<\/b><\/span><\/span>um\u00a0<\/b><\/span><\/span>gerador ideal\u00a0<\/b><\/span><\/span>e um\u00a0<\/b><\/span><\/span>receptor ideal.<\/b><\/span><\/span>\u00a0A\u00a0<\/b><\/span><\/span>pot\u00eancia el\u00e9trica dissipada<\/b><\/span><\/span>\u00a0no\u00a0<\/b><\/span><\/span>resistor de 4 \u2126\u00a0<\/b><\/span><\/span>do circuito \u00e9:<\/b><\/span><\/span><\/span><\/span><\/p>\n

a)\u00a0<\/b><\/span><\/span>0,16 W.<\/b><\/span><\/span><\/span><\/span><\/p>\n

b)\u00a0<\/b><\/span><\/span>0,20 W.<\/b><\/span><\/span><\/span><\/span><\/p>\n

c)\u00a0<\/b><\/span><\/span>0,40 W.<\/b><\/span><\/span><\/span><\/span><\/p>\n

d)\u00a0<\/b><\/span><\/span>0,72 W.<\/b><\/span><\/span><\/span><\/span><\/p>\n

e)\u00a0<\/b><\/span><\/span>0,80 W.<\/b><\/span><\/span><\/span><\/span><\/p>\n

 <\/p>\n

29-(PUC-RJ-016)<\/b><\/span><\/span><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Um estudante arma um circuito el\u00e9trico simples a partir de uma bateria de\u00a0<\/b><\/span><\/span>15 V<\/b><\/span><\/span>\u00a0e\u00a0<\/b><\/span><\/span>tr\u00eas resistores id\u00eanticos de 10 k\u2126<\/b><\/span><\/span>. Com um amper\u00edmetro, ele <\/b><\/span><\/span>mede uma corrente de 1,0 mA que passa em um dos resistores<\/b><\/span><\/span>. Qual \u00e9 a <\/b><\/span><\/span>resist\u00eancia equivalente do circuito<\/b><\/span><\/span>, em k\u2126?<\/b><\/span><\/span><\/span><\/span><\/p>\n

(A) 3,3<\/b><\/span><\/span><\/span><\/span><\/p>\n

(B) 5,0<\/b><\/span><\/span><\/span><\/span><\/p>\n

(C) 10<\/b><\/span><\/span><\/span><\/span><\/p>\n

(D) 15<\/b><\/span><\/span><\/span><\/span><\/p>\n

(E) 30<\/b><\/span><\/span><\/span><\/span><\/p>\n

30-(UEM-PR-015)<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Considere um circuito el\u00e9trico composto de dois ramos paralelos,\u00a0<\/b><\/span><\/span>A\u00a0<\/b><\/i><\/span><\/span>e\u00a0<\/b><\/span><\/span>B<\/b><\/i><\/span><\/span>, que \u00e9 alimentado por uma bateria de 10 V ligada em paralelo com o circuito.<\/b><\/span><\/span><\/p>\n

O ramo\u00a0<\/b><\/span><\/span>A\u00a0<\/b><\/i><\/span><\/span>\u00e9 constitu\u00eddo por tr\u00eas resistores ligados em s\u00e9rie, enquanto o ramo\u00a0<\/b><\/span><\/span>B\u00a0<\/b><\/i><\/span><\/span>\u00e9 constitu\u00eddo por<\/b><\/span><\/span><\/p>\n

\"\"<\/p>\n

dois resistores ligados em paralelo. Considere que todos os resistores do circuito s\u00e3o<\/b><\/span><\/span><\/p>\n

\u00f4hmicos e possuem resist\u00eancia el\u00e9trica de 10 \u2126.<\/b><\/span><\/span><\/p>\n

Com base nessas informa\u00e7\u00f5es, assinale o que for correto.<\/b><\/span><\/span><\/p>\n

01)<\/b><\/span><\/span>\u00a0Os resistores equivalentes nos dois ramos do circuito possuem, respectivamente, resist\u00eancia el\u00e9trica de 30 \u2126 e de 5 \u2126.<\/b><\/span><\/span><\/p>\n

02)<\/b><\/span><\/span>\u00a0A corrente el\u00e9trica que flui no ramo\u00a0<\/b><\/span><\/span>A\u00a0<\/b><\/i><\/span><\/span>\u00e9 de 2 A.<\/b><\/span><\/span><\/p>\n

04)<\/b><\/span><\/span>\u00a0A pot\u00eancia dissipada no ramo\u00a0<\/b><\/span><\/span>B\u00a0<\/b><\/i><\/span><\/span>\u00e9 de 20 W.<\/b><\/span><\/span><\/p>\n

08)<\/b><\/span><\/span>\u00a0A pot\u00eancia dissipada e a corrente el\u00e9trica no ramo\u00a0<\/b><\/span><\/span>B\u00a0<\/b><\/i><\/span><\/span>s\u00e3o maiores que as observadas no ramo\u00a0<\/b><\/span><\/span>A<\/b><\/i><\/span><\/span>.<\/b><\/span><\/span><\/p>\n

16)<\/b><\/span><\/span>\u00a0A diferen\u00e7a de potencial entre os terminais do segundo resistor do ramo\u00a0<\/b><\/span><\/span>A\u00a0<\/b><\/i><\/span><\/span>\u00e9 de aproximadamente 3,3<\/b><\/span><\/span>\u00a0V<\/b><\/span><\/span><\/span><\/p>\n

Geradores<\/span><\/span><\/span><\/p>\n

31-(UFPR-PR-015)<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

A\u00a0<\/b><\/span><\/span>fun\u00e7\u00e3o principal de geradores el\u00e9tricos \u00e9<\/b><\/span><\/span>\u00a0<\/b><\/span><\/span>transformar em energia el\u00e9trica algum outro tipo de energia.<\/b><\/span><\/span><\/p>\n

No caso de\u00a0<\/b><\/span><\/span>geradores elementares de corrente cont\u00ednua<\/b><\/span><\/span>, cujo <\/b><\/span><\/span>circuito equivalente<\/b><\/span><\/span>\u00a0est\u00e1 mostrado abaixo, onde\u00a0<\/b><\/span><\/span>r \u00e9 a resist\u00eancia interna do gerador e\u00a0\u03b5\u00a0sua for\u00e7a eletromotriz<\/b><\/span><\/span>, o comportamento caracter\u00edstico \u00e9 descrito pela conhecida\u00a0<\/b><\/span><\/span>equa\u00e7\u00e3o do gerador<\/b><\/span><\/span>, que fornece a\u00a0<\/b><\/span><\/span>diferen\u00e7a de potencial <\/b><\/span><\/span>\u0394V\u00a0<\/b><\/span><\/span>em seus terminais\u00a0<\/b><\/span><\/span>A e B<\/b><\/span><\/span>\u00a0em fun\u00e7\u00e3o da corrente\u00a0<\/b><\/span><\/span>i\u00a0<\/b><\/span><\/span>fornecida por ele<\/b><\/span><\/span>. Um\u00a0<\/b><\/span><\/span>dado gerador tem a curva caracter\u00edstica mostrada no gr\u00e1fico abaixo.<\/b><\/span><\/span><\/p>\n

\"\"<\/p>\n

A partir do\u00a0<\/b><\/span><\/span>circuito e do gr\u00e1fico<\/b><\/span><\/span>\u00a0apresentados, assinale a<\/b><\/span><\/span>alternativa correta para a<\/b><\/span><\/span>\u00a0<\/b><\/span><\/span>pot\u00eancia dissipada internamente na fonte quando esta fornece uma\u00a0<\/b><\/span><\/span>corrente<\/b><\/span><\/span>\u00a0<\/b><\/span><\/span>de 2,0 mA.<\/b><\/span><\/span><\/p>\n

\"\"<\/p>\n

Aparelhos de medi\u00e7\u00e3o el\u00e9trica (amper\u00edmetros e volt\u00edmetros)<\/span><\/span><\/span><\/p>\n

32-(COL\u00c9GIO NAVAL-015)<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Considere que um determinado\u00a0<\/b><\/span><\/span>estudante utilizando resistores dispon\u00edveis<\/b><\/span><\/span>, no\u00a0<\/b><\/span><\/span>laborat\u00f3rio de sua escola, montou os circuitos mostrados abaixo:<\/b><\/span><\/span><\/p>\n

\"\"<\/p>\n

Querendo fazer algumas medidas el\u00e9tricas,\u00a0<\/b><\/span><\/span>usou um\u00a0<\/b><\/span><\/span>volt\u00edmetro (V)\u00a0<\/b><\/span><\/span>para medir a\u00a0<\/b><\/span><\/span>tens\u00e3o<\/b><\/span><\/span>\u00a0e um\u00a0<\/b><\/span><\/span>amper\u00edmetro (A)\u00a0<\/b><\/span><\/span>para medir a\u00a0<\/b><\/span><\/span>intensidade da corrente el\u00e9trica.<\/b><\/span><\/span><\/p>\n

Considerando todos os elementos envolvidos como\u00a0<\/b><\/span><\/span>sendo ideais<\/b><\/span><\/span>, os<\/b><\/span><\/span>valores\u00a0<\/b><\/span><\/span>medidos pelo\u00a0<\/b><\/span><\/span>volt\u00edmetro (situa\u00e7\u00e3o 1) e pelo amper\u00edmetro (situa\u00e7\u00e3o 2)\u00a0<\/b><\/span><\/span>foram, respectivamente:<\/b><\/span><\/span><\/p>\n

(A)\u00a0<\/b><\/span><\/span>2V e 1,2A\u00a0<\/b><\/span><\/span><\/p>\n

(B)\u00a0<\/b><\/span><\/span>4V e 1,2 A<\/b><\/span><\/span><\/p>\n

C)\u00a0<\/b><\/span><\/span>2V e 2,4 A<\/b><\/span><\/span><\/p>\n

(D)\u00a0<\/b><\/span><\/span>4V e 2,4A\u00a0<\/b><\/span><\/span>(<\/b><\/span><\/span><\/p>\n

E)\u00a0<\/b><\/span><\/span>6V e 1,2 A<\/b><\/span><\/span><\/p>\n

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

33-<\/span><\/span><\/span>(FUVEST-SP-016)<\/b><\/span><\/span><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

\"\"<\/p>\n

\"\"<\/p>\n

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

34-(FAMERP-SP-017)<\/b><\/span><\/span><\/span><\/span><\/span><\/p>\n

A\u00a0<\/b><\/span><\/span>figura\u00a0<\/b><\/span><\/span>representa o\u00a0<\/b><\/span><\/span>esquema de liga\u00e7\u00e3o dos far\u00f3is de um autom\u00f3vel \u00e0 bateria do ve\u00edculo.<\/b><\/span><\/span><\/span><\/span>\"\"<\/p>\n

O\u00a0<\/b><\/span><\/span>circuito<\/b><\/span><\/span>\u00a0\u00e9\u00a0<\/b><\/span><\/span>constitu\u00eddo <\/b><\/span><\/span>por:\u00a0<\/b><\/span><\/span>duas l\u00e2mpadas de 12 V \u2013 60 W cada uma<\/b><\/span><\/span>; uma\u00a0<\/b><\/span><\/span>chave de acionamento\u00a0<\/b><\/span><\/span>e um <\/b><\/span><\/span>fus\u00edvel de prote\u00e7\u00e3o, ambos\u00a0<\/b><\/span><\/span>de\u00a0<\/b><\/span><\/span>resist\u00eancias desprez\u00edveis<\/b><\/span><\/span>; e\u00a0<\/b><\/span><\/span>fios de liga\u00e7\u00e3o e conectores<\/b><\/span><\/span>, tamb\u00e9m\u00a0<\/b><\/span><\/span>ideais.<\/b><\/span><\/span><\/span><\/span><\/p>\n

Se os\u00a0<\/b><\/span><\/span>dois far\u00f3is estiverem acesos,\u00a0<\/b><\/span><\/span>das <\/b><\/span><\/span>op\u00e7\u00f5es indicadas nas alternativas,\u00a0<\/b><\/span><\/span>aquela que\u00a0<\/b><\/span><\/span>corresponde \u00e0 menor amperagem do fus\u00edvel capaz de proteger\u00a0<\/b><\/span><\/span>esse circuito \u00e9<\/b><\/span><\/span><\/span><\/span><\/p>\n

(A)\u00a0<\/b><\/span><\/span>15 A.<\/b><\/span><\/span><\/span><\/span><\/p>\n

(B)\u00a0<\/b><\/span><\/span>12 A.<\/b><\/span><\/span><\/span><\/span><\/p>\n

(C)\u00a0<\/b><\/span><\/span>6 A.<\/b><\/span><\/span><\/span><\/span><\/p>\n

(D)\u00a0<\/b><\/span><\/span>4 A.<\/b><\/span><\/span><\/span><\/span><\/p>\n

(E)\u00a0<\/b><\/span><\/span>9 A.<\/b><\/span><\/span><\/span><\/span><\/p>\n

35-(COL\u00c9GIO NAVAL-015<\/b><\/span><\/span><\/span>)<\/b><\/span><\/span><\/p>\n

\"\"<\/p>\n

Considere que um determinado\u00a0<\/b><\/span><\/span>estudante utilizando resistores dispon\u00edveis<\/b><\/span><\/span>, no\u00a0<\/b><\/span><\/span>laborat\u00f3rio de sua escola, montou os circuitos mostrados abaixo:<\/b><\/span><\/span><\/p>\n

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

Querendo fazer algumas medidas el\u00e9tricas,\u00a0<\/b><\/span><\/span>usou um\u00a0<\/b><\/span><\/span>volt\u00edmetro (V)\u00a0<\/b><\/span><\/span>para medir a\u00a0<\/b><\/span><\/span>tens\u00e3o<\/b><\/span><\/span>\u00a0e um\u00a0<\/b><\/span><\/span>amper\u00edmetro (A)\u00a0<\/b><\/span><\/span>para medir a\u00a0<\/b><\/span><\/span>intensidade da corrente el\u00e9trica.<\/b><\/span><\/span><\/p>\n

Considerando todos os elementos envolvidos como\u00a0<\/b><\/span><\/span>sendo ideais<\/b><\/span><\/span>, os <\/b><\/span><\/span>valores\u00a0<\/b><\/span><\/span>medidos pelo\u00a0<\/b><\/span><\/span>volt\u00edmetro (situa\u00e7\u00e3o 1) e pelo amper\u00edmetro (situa\u00e7\u00e3o 2)\u00a0<\/b><\/span><\/span>foram, respectivamente:<\/b><\/span><\/span><\/p>\n

(A)\u00a0<\/b><\/span><\/span>2V e 1,2A\u00a0<\/b><\/span><\/span><\/p>\n

(B)\u00a0<\/b><\/span><\/span>4V e 1,2\u00aa<\/b><\/span><\/span><\/p>\n

C)\u00a0<\/b><\/span><\/span>2V e 2,4A\u00a0<\/b><\/span><\/span><\/p>\n

(D)\u00a0<\/b><\/span><\/span>4V e 2,4A\u00a0<\/b><\/span><\/span><\/p>\n

(E)\u00a0<\/b><\/span><\/span>6V e 1,2A<\/b><\/span><\/span><\/p>\n

 <\/p>\n

Confira as resolu\u00e7\u00f5es comentadas<\/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 – 2017 \u2013 2016 – 2015 Corrente el\u00e9trica 01-UNICAMP-SP-017) Tecnologias m\u00f3veis como celulares e\u00a0tablets\u00a0t\u00eam\u00a0tempo\u00a0de\u00a0autonomia limitado\u00a0pela\u00a0carga armazenada\u00a0em suas\u00a0baterias. O\u00a0gr\u00e1fico abaixo\u00a0apresenta, de\u00a0forma simplificada,\u00a0a\u00a0corrente de recarga de uma\u00a0c\u00e9lula de bateria\u00a0de \u00edon de l\u00edtio, em fun\u00e7\u00e3o do tempo. Considere uma\u00a0c\u00e9lula de bateria inicialmente descarregada\u00a0e que\u00a0\u00e9 carregada seguindo essa curva de corrente. A sua\u00a0carga no final da recarga\u00a0\u00e9 de 02-(FMJ-SP-017) O gr\u00e1fico<\/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-3302","page","type-page","status-publish","hentry"],"aioseo_notices":[],"_links":{"self":[{"href":"https:\/\/fisicaevestibular.com.br\/novo\/wp-json\/wp\/v2\/pages\/3302","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=3302"}],"version-history":[{"count":4,"href":"https:\/\/fisicaevestibular.com.br\/novo\/wp-json\/wp\/v2\/pages\/3302\/revisions"}],"predecessor-version":[{"id":9902,"href":"https:\/\/fisicaevestibular.com.br\/novo\/wp-json\/wp\/v2\/pages\/3302\/revisions\/9902"}],"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=3302"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}