{"id":4848,"date":"2020-01-09T14:10:43","date_gmt":"2020-01-09T14:10:43","guid":{"rendered":"http:\/\/fisicaevestibular.com.br\/novo\/?page_id=4848"},"modified":"2024-06-30T00:12:19","modified_gmt":"2024-06-30T00:12:19","slug":"eletrodinamica-2018-2019","status":"publish","type":"page","link":"https:\/\/fisicaevestibular.com.br\/novo\/vestibulares-recentes\/eletricidade\/eletrodinamica-2018-2019\/","title":{"rendered":"Eletrodin\u00e2mica \u2013 2018\/2019"},"content":{"rendered":"

Eletrodin\u00e2mica \u2013 2018\/2019<\/span><\/span><\/span><\/p>\n

Corrente el\u00e9trica \u2013 Resist\u00eancia el\u00e9trica, Pot\u00eancia el\u00e9trica e Energia el\u00e9trica<\/span><\/span><\/span><\/p>\n

01-(ENEM-MEC-018)<\/b><\/span><\/span><\/span><\/span><\/span><\/p>\n

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02-(ENEM-MEC-018)<\/span><\/span><\/span><\/p>\n

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03-(MEDICINA -UNIVERSIDADE MUNICIPAL DE S\u00c3O CAETANO DO SUL \u2013\u2013 USCS-SP \u2013 019)<\/b><\/span><\/span><\/span><\/span><\/span><\/p>\n

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Para carregar a bateria de um smartphone, foi utilizado um carregador que fornece uma diferen\u00e7a de potencial de 5,0 V<\/b><\/span><\/span>\u00a0e\u00a0<\/b><\/span><\/span>uma corrente el\u00e9trica de intensidade 2,0 A,<\/b><\/span><\/span>\u00a0supostamente\u00a0<\/b><\/span><\/span>constantes durante todo o processo de carga.<\/b><\/span><\/span><\/span><\/span><\/p>\n

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Considerando que\u00a0<\/b><\/span><\/span>toda energia fornecida pelo carregador \u00e9 acumulada na bateria, que a quantidade total de energia que a bateria pode armazenar \u00e9 1,0.105\u00a0J\u00a0<\/b><\/span><\/span>e que\u00a0<\/b><\/span><\/span>no in\u00edcio do processo de carregamento ela possu\u00eda apenas 10% da sua capacidade total,<\/b><\/span><\/span>\u00a0o\u00a0<\/b><\/span><\/span>intervalo de tempo entre o in\u00edcio do processo e o instante em que a bateria atingiu a carga total<\/b><\/span><\/span>\u00a0foi<\/b><\/span><\/span><\/span><\/span><\/p>\n

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

04-(ESCOLA T\u00c9CNICA ESTADUAL \u2013 ETEC \u2013 SP \u2013 019)<\/b><\/span><\/span><\/span><\/p>\n

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O\u00a0<\/b><\/span><\/span><\/span>Electrophorus electricus<\/b><\/i><\/span><\/span><\/span>, popularmente conhecido por poraqu\u00ea ou treme-treme,\u00a0<\/b><\/span><\/span><\/span>\u00e9 um\u00a0<\/b><\/span><\/span><\/span>peixe carn\u00edvoro de agua doce encontrado na Bacia Amaz\u00f4nica.<\/b><\/span><\/span><\/span><\/p>\n

Esse peixe\u00a0<\/b><\/span><\/span><\/span>\u00e9 capaz de liberar uma forte descarga el\u00e9trica, imobilizando e at\u00e9 matando suas presas ou agressores.<\/b><\/span><\/span><\/span>\u00a0Isso \u00e9 poss\u00edvel porque,\u00a0<\/b><\/span><\/span><\/span>logo apos sua cabe\u00e7a, estende-se uma serie de c\u00e9lulas, conectadas entre si, ate a cauda.<\/b><\/span><\/span><\/span><\/p>\n

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Essa\u00a0<\/b><\/span><\/span><\/span>serie de c\u00e9lulas permite que a cabe\u00e7a desse peixe tenha carga positiva enquanto a extremidade de sua cauda tenha carga negativa.<\/b><\/span><\/span><\/span><\/p>\n

Assinale a\u00a0<\/b><\/span><\/span><\/span>alternativa que apresenta um objeto do cotidiano que tem caracter\u00edsticas compar\u00e1veis as desse peixe.<\/b><\/span><\/span><\/span><\/p>\n

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

(B)\u00a0<\/b><\/span><\/span><\/span>Motor el\u00e9trico<\/b><\/span><\/span><\/span><\/p>\n

(C)\u00a0<\/b><\/span><\/span><\/span>Bateria de carro<\/b><\/span><\/span><\/span><\/p>\n

(D)\u00a0<\/b><\/span><\/span><\/span>Ferro de passar roupas<\/b><\/span><\/span><\/span><\/p>\n

(E)\u00a0<\/b><\/span><\/span><\/span>L\u00e2mpada incandescente<\/b><\/span><\/span><\/span><\/p>\n

05-(ESCOLA T\u00c9CNICA ESTADUAL \u2013 ETEC \u2013 SP \u2013 019)<\/b><\/span><\/span><\/span><\/p>\n

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Em\u00a0<\/b><\/span><\/span><\/span>uma ind\u00fastria, um t\u00e9cnico nota, com o uso de um amper\u00edmetro,\u00a0<\/b><\/span><\/span><\/span>que o\u00a0<\/b><\/span><\/span><\/span>consumo de Intensidade de corrente em uma de suas m\u00e1quinas est\u00e1 aumentando diariamente, provavelmente, devido a algum<\/b><\/span><\/span><\/span><\/p>\n

defeito na parte el\u00e9trica da m\u00e1quina.<\/b><\/span><\/span><\/span><\/p>\n

O t\u00e9cnico, a princ\u00edpio, n\u00e3o se preocupa pelo fato de a m\u00e1quina possuir disjuntores de prote\u00e7\u00e3o.<\/b><\/span><\/span><\/span><\/p>\n

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Sabendo que o\u00a0<\/b><\/span><\/span><\/span>amper\u00edmetro utilizado s\u00f3 indica intensidade de corrente em miliamperes\u00a0<\/b><\/span><\/span><\/span>e que os\u00a0<\/b><\/span><\/span><\/span>disjuntores s\u00e3o de 10 Amperes,<\/b><\/span><\/span><\/span>\u00a0no\u00a0<\/b><\/span><\/span><\/span>momento em que os disjuntores desarmarem, a indica\u00e7\u00e3o no amper\u00edmetro, provavelmente, ser\u00e1 de,\u00a0<\/b><\/span><\/span><\/span>aproximadamente:<\/b><\/span><\/span><\/span><\/p>\n

(A)\u00a0<\/b><\/span><\/span><\/span>10 mA.<\/b><\/span><\/span><\/span><\/p>\n

(B)\u00a0<\/b><\/span><\/span><\/span>1000 mA.<\/b><\/span><\/span><\/span><\/p>\n

(C)\u00a0<\/b><\/span><\/span><\/span>10000 mA.<\/b><\/span><\/span><\/span><\/p>\n

(D)\u00a0<\/b><\/span><\/span><\/span>100000 mA.<\/b><\/span><\/span><\/span><\/p>\n

(E)\u00a0<\/b><\/span><\/span><\/span>1000000 mA.<\/b><\/span><\/span><\/span><\/p>\n

06-(PUC \u2013 RIO \u2013 019)<\/b><\/span><\/span><\/span><\/p>\n

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Uma\u00a0<\/b><\/span><\/span><\/span>diferen\u00e7a de potencial V \u00e9 aplicada a um resistor de resist\u00eancia R.\u00a0<\/b><\/span><\/span><\/span>A\u00a0<\/b><\/span><\/span><\/span>pot\u00eancia dissipada nesse resistor \u00e9 P.<\/b><\/span><\/span><\/span><\/p>\n

Ao dobrar a resist\u00eancia e triplicar a diferen\u00e7a de potencial, a nova pot\u00eancia dissipada\u00a0<\/b><\/span><\/span><\/span>ser\u00e1:<\/b><\/span><\/span><\/span><\/p>\n

A)\u00a0<\/b><\/span><\/span><\/span>6P\u00a0<\/b><\/span><\/span><\/span>B)\u00a0<\/b><\/span><\/span><\/span>3P\u00a0<\/b><\/span><\/span><\/span>C)\u00a0<\/b><\/span><\/span><\/span>P\u00a0<\/b><\/span><\/span><\/span>D)\u00a0<\/b><\/span><\/span><\/span>2P\u00a0<\/b><\/span><\/span><\/span>E)\u00a0<\/b><\/span><\/span><\/span>9P\/2<\/b><\/span><\/span><\/span><\/p>\n

07-(CEDERJ \u2013 RJ \u2013 meio do ano \u2013 019\/029)<\/b><\/span><\/span><\/span><\/p>\n

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Disjuntor \u00e9 um dispositivo de seguran\u00e7a que impede a passagem de corrente el\u00e9trica em um circuito quando ela atinge um valor superior ao recomendado.<\/b><\/span><\/span><\/span><\/p>\n

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Um\u00a0<\/b><\/span><\/span><\/span>chuveiro el\u00e9\u00adtrico, cuja pot\u00eancia \u00e9 de 5,5\u00d7103<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/span>W,\u00a0<\/b><\/span><\/span><\/span>necessita ser\u00a0<\/b><\/span><\/span><\/span>instalado em uma resid\u00eancia onde a tens\u00e3o \u00e9 de 220 V.<\/b><\/span><\/span><\/span>\u00a0O\u00a0<\/b><\/span><\/span><\/span>disjuntor adequado para a instala\u00e7\u00e3o desse chuveiro deve ser\u00a0<\/b><\/span><\/span><\/span>de<\/b><\/span><\/span><\/span><\/p>\n

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

08-(ACAFE \u2013\u00a0Associa\u00e7\u00e3o Catarinense das Funda\u00e7\u00f5es Educacionais \u2013Medicina \u2013 2019.<\/b><\/span><\/span><\/span><\/p>\n

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O\u00a0<\/b><\/span><\/span><\/span>quadro abaixo apresenta algumas informa\u00e7\u00f5es\u00a0<\/b><\/span><\/span><\/span>de uma\u00a0<\/b><\/span><\/span><\/span>fatura da conta de energia el\u00e9trica\u00a0<\/b><\/span><\/span><\/span>de uma\u00a0<\/b><\/span><\/span><\/span>resid\u00eancia por um per\u00edodo de 30 dias.<\/b><\/span><\/span><\/span><\/p>\n

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Sabe-se que uma\u00a0<\/b><\/span><\/span><\/span>chaleira el\u00e9trica \u00e9 utilizada todos os dias por quinze minutos\u00a0<\/b><\/span><\/span><\/span>e que\u00a0<\/b><\/span><\/span><\/span>a energia gasta por ela, em 30 dias, representa 2% do consumo de energia da casa.<\/b><\/span><\/span><\/span><\/p>\n

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A\u00a0<\/b><\/span><\/span><\/span>alternativa correta que apresenta o valor da pot\u00eancia dessa chaleira, em watt,\u00a0<\/b><\/span><\/span><\/span>\u00e9:<\/b><\/span><\/span><\/span><\/p>\n

A<\/b><\/span><\/span><\/span>\u00a01500
\n<\/b><\/span><\/span><\/span>B\u00a0<\/b><\/span><\/span><\/span>1200
\n<\/b><\/span><\/span><\/span>C\u00a0<\/b><\/span><\/span><\/span>1000
\n<\/b><\/span><\/span><\/span>D<\/b><\/span><\/span><\/span>\u00a0800<\/b><\/span><\/span><\/span><\/p>\n

09-(UDESC-SC-019)<\/b><\/span><\/span><\/span><\/p>\n

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Considere que o\u00a0<\/b><\/span><\/span><\/span>valor m\u00e9dio do kWh \u00e9 de R$ 0,50.\u00a0<\/b><\/span><\/span><\/span>Um\u00a0<\/b><\/span><\/span><\/span>chuveiro el\u00e9trico tem uma pot\u00eancia de 7000<\/b><\/span><\/span><\/span><\/p>\n

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W e uma l\u00e2mpada tem uma pot\u00eancia de 100 W.<\/b><\/span><\/span><\/span><\/p>\n

Assinale a\u00a0<\/b><\/span><\/span><\/span>alternativa que corresponde, respectivamente, ao valor do consumo de energia, em 30 dias, de uma pessoa que fica em m\u00e9dia 20 minutos tomando banho diariamente, e ao valor do consumo de uma l\u00e2mpada o dia inteiro ligada.<\/b><\/span><\/span><\/span><\/p>\n

A.\u00a0<\/b><\/span><\/span><\/span>( ) R$ 35,00 e R$ 36,00<\/b><\/span><\/span><\/span><\/p>\n

B.\u00a0<\/b><\/span><\/span><\/span>( ) R$ 14,00 e R$ 14,40<\/b><\/span><\/span><\/span><\/p>\n

C.\u00a0<\/b><\/span><\/span><\/span>( ) R$ 35,00 e R$ 14,00<\/b><\/span><\/span><\/span><\/p>\n

D.\u00a0<\/b><\/span><\/span><\/span>( ) R$ 14,00 e R$ 36,00<\/b><\/span><\/span><\/span><\/p>\n

E.\u00a0<\/b><\/span><\/span><\/span>( ) R$ 35,00 e R$ 14,40<\/b><\/span><\/span><\/span><\/p>\n

10-Instituto Federal de Educa\u00e7\u00e3o, Ci\u00eancia e Tecnologia do<\/b><\/span><\/span><\/span><\/p>\n

Paran\u00e1\u00a0(IFPR) \u2013 2019<\/b><\/span><\/span><\/span><\/p>\n

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Um\u00a0<\/b><\/span><\/span><\/span>chuveiro el\u00e9trico apresenta uma etiqueta com os seguintes dados nominais<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/span>fornecidos pelo<\/b><\/span><\/span><\/span><\/p>\n

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fabricante: P = 4400 W e V = 220 V.<\/b><\/span><\/span><\/span><\/p>\n

Utilizando essas informa\u00e7\u00f5es, assinale a alternativa correta.<\/b><\/span><\/span><\/span><\/p>\n

A)\u00a0<\/b><\/span><\/span><\/span>Se o chuveiro for ligado em V = 110 V, funcionar\u00e1 com o qu\u00e1druplo de sua pot\u00eancia nominal.<\/b><\/span><\/span><\/span><\/p>\n

B)\u00a0<\/b><\/span><\/span><\/span>Caso o chuveiro seja ligado em 110 V, \u201cqueimar\u00e1\u201d imediatamente, porque a corrente el\u00e9trica circulante ser\u00e1 o dobro que necessita para o correto funcionamento.<\/b><\/span><\/span><\/span><\/p>\n

C)\u00a0<\/b><\/span><\/span><\/span>O chuveiro n\u00e3o aquecer\u00e1 a \u00e1gua adequadamente, se for ligado em 110 V. A pot\u00eancia de opera\u00e7\u00e3o ser\u00e1 1\/4 da nominal e a corrente el\u00e9trica circulante ser\u00e1 apenas a metade.<\/b><\/span><\/span><\/span><\/p>\n

D)\u00a0<\/b><\/span><\/span><\/span>Ligado em 110 V, a pot\u00eancia ser\u00e1 a mesma, mas a corrente el\u00e9trica ficar\u00e1 reduzida a um quarto.<\/b><\/span><\/span><\/span><\/p>\n

11-(UEMG-MG-019)<\/b><\/span><\/span><\/span><\/p>\n

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12-Universidade Federal de Uberl\u00e2ndia\u00a0\u2013\u00a0UFU\u00a0\u2013 MG \u2013 meio do ano \u2013 2019\/2020<\/b><\/span><\/span><\/span><\/p>\n

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Um\u00a0<\/b><\/span><\/span><\/span>circuito, utilizando um conjunto gerador de c\u00e9lulas fotovoltaicas<\/b><\/span><\/span><\/span>\u00a0e\u00a0<\/b><\/span><\/span><\/span>um resistor, \u00e9 montado conforme mostra a Figura A.<\/b><\/span><\/span><\/span>\u00a0O\u00a0<\/b><\/span><\/span><\/span>gr\u00e1fico da Figura B indica as curvas de Diferen\u00e7a De Potencial (DDP) em fun\u00e7\u00e3o da corrente el\u00e9trica do conjunto gerador de c\u00e9lulas fotovoltaicas e do resistor indicados na Figura A.<\/b><\/span><\/span><\/span><\/p>\n

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Qual a pot\u00eancia que o conjunto gerador de c\u00e9lulas fotovoltaicas fornece ao resistor nas condi\u00e7\u00f5es do circuito da Figura A?<\/b><\/span><\/span><\/span><\/p>\n

A)\u00a0<\/b><\/span><\/span><\/span>1,60 W.\u00a0<\/b><\/span><\/span><\/span>B)\u00a0<\/b><\/span><\/span><\/span>0,21 W<\/b><\/span><\/span><\/span>. C)\u00a0<\/b><\/span><\/span><\/span>0,30 W.\u00a0<\/b><\/span><\/span><\/span>D)\u00a0<\/b><\/span><\/span><\/span>1,40 W<\/b><\/span><\/span><\/span><\/p>\n

13-(UFAM-AM-2019)<\/b><\/span><\/span><\/span><\/p>\n

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14-(UEMA-MA-019)<\/b><\/span><\/span><\/span><\/p>\n

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A\u00a0<\/b><\/span><\/span><\/span>corrente el\u00e9trica designa o movimento ordenado de cargas el\u00e9tricas\u00a0<\/b><\/span><\/span><\/span>(part\u00edculas eletrizadas chamadas de \u00edons ou el\u00e9trons)\u00a0<\/b><\/span><\/span><\/span>dentro de um sistema condutor.<\/b><\/span><\/span><\/span><\/p>\n

Esse\u00a0<\/b><\/span><\/span><\/span>sistema apresenta uma diferen\u00e7a de potencial el\u00e9trico (ddp)\u00a0<\/b><\/span><\/span><\/span>ou\u00a0<\/b><\/span><\/span><\/span>tens\u00e3o el\u00e9trica.<\/b><\/span><\/span><\/span><\/p>\n

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Qual ser\u00e1 o valor da intensidade da corrente el\u00e9trica\u00a0<\/b><\/span><\/span><\/span>de um\u00a0<\/b><\/span><\/span><\/span>ferro el\u00e9trico\u00a0<\/b><\/span><\/span><\/span>que\u00a0<\/b><\/span><\/span><\/span>est\u00e1 ligado a uma tens\u00e3o de 220 V\u00a0<\/b><\/span><\/span><\/span>e que possui uma\u00a0<\/b><\/span><\/span><\/span>resist\u00eancia de 22 \u03a9?<\/b><\/span><\/span><\/span><\/p>\n

a)\u00a0<\/b><\/span><\/span><\/span>11 A\u00a0<\/b><\/span><\/span><\/span>b)\u00a0<\/b><\/span><\/span><\/span>22 A\u00a0<\/b><\/span><\/span><\/span>c)\u00a0<\/b><\/span><\/span><\/span>10 A\u00a0<\/b><\/span><\/span><\/span>d)\u00a0<\/b><\/span><\/span><\/span>220 A\u00a0<\/b><\/span><\/span><\/span>e)\u00a0<\/b><\/span><\/span><\/span>4840 A<\/b><\/span><\/span><\/span><\/p>\n

15-(Universidade Estadual do Rio Grande do Sul \u2013 UERGS \u2013 019)<\/b><\/span><\/span><\/span><\/p>\n

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Um resistor \u00f4hmico ligado a uma tens\u00e3o de 20 V desenvolve uma pot\u00eancia de 300 W<\/b><\/span><\/span><\/span>.<\/b><\/span><\/span><\/span><\/p>\n

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A\u00a0<\/b><\/span><\/span><\/span>corrente que circula pelo resistor<\/b><\/span><\/span><\/span>\u00a0e a\u00a0<\/b><\/span><\/span><\/span>energia gasta em um minuto s\u00e3o, respectivamente<\/b><\/span><\/span><\/span>,<\/b><\/span><\/span><\/span><\/p>\n

A)\u00a0<\/b><\/span><\/span><\/span>6 A e 300 J<\/b><\/span><\/span><\/span><\/p>\n

B)\u00a0<\/b><\/span><\/span><\/span>6 A e 6000 J<\/b><\/span><\/span><\/span><\/p>\n

C)\u00a0<\/b><\/span><\/span><\/span>6 A e 18000 J<\/b><\/span><\/span><\/span><\/p>\n

D)\u00a0<\/b><\/span><\/span><\/span>15 A e 6000 J<\/b><\/span><\/span><\/span><\/p>\n

E)\u00a0<\/b><\/span><\/span><\/span>15 A e 18000 J<\/b><\/span><\/span><\/span><\/p>\n

16-(ENEM-MEC-017)<\/b><\/span><\/span><\/span><\/p>\n

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Dispositivos eletr\u00f4nicos<\/b><\/span><\/span><\/span>\u00a0que\u00a0<\/b><\/span><\/span><\/span>utilizam materiais de baixo custo,\u00a0<\/b><\/span><\/span><\/span>como\u00a0<\/b><\/span><\/span><\/span>pol\u00edmeros semicondutores,<\/b><\/span><\/span><\/span>\u00a0t\u00eam<\/b><\/span><\/span><\/span><\/p>\n

sido\u00a0<\/b><\/span><\/span><\/span>desenvolvidos para monitorar a concentra\u00e7\u00e3o de am\u00f4nia\u00a0<\/b><\/span><\/span><\/span>(g\u00e1s t\u00f3xico e incolor) em\u00a0<\/b><\/span><\/span><\/span>granjas av\u00edcolas.<\/b><\/span><\/span><\/span><\/p>\n

A\u00a0<\/b><\/span><\/span><\/span>polianilina \u00e9 um pol\u00edmero semicondutor\u00a0<\/b><\/span><\/span><\/span>que tem o\u00a0<\/b><\/span><\/span><\/span>valor de sua resist\u00eancia el\u00e9trica nominal quadruplicado quando exposta a altas concentra\u00e7\u00f5es de am\u00f4nia.<\/b><\/span><\/span><\/span><\/p>\n

Na\u00a0<\/b><\/span><\/span><\/span>aus\u00eancia de am\u00f4nia,<\/b><\/span><\/span><\/span>\u00a0a\u00a0<\/b><\/span><\/span><\/span>polianilina\u00a0<\/b><\/span><\/span><\/span>se\u00a0<\/b><\/span><\/span><\/span>comporta como um resistor \u00f4hmico\u00a0<\/b><\/span><\/span><\/span>e a\u00a0<\/b><\/span><\/span><\/span>sua resposta el\u00e9trica \u00e9 mostrada no gr\u00e1fico.<\/b><\/span><\/span><\/span><\/p>\n

<\/p>\n

O\u00a0<\/b><\/span><\/span><\/span>valor da resist\u00eancia el\u00e9trica da polianilina\u00a0<\/b><\/span><\/span><\/span>na presen\u00e7a de\u00a0<\/b><\/span><\/span><\/span>altas concentra\u00e7\u00f5es de am\u00f4nia,<\/b><\/span><\/span><\/span>\u00a0em\u00a0<\/b><\/span><\/span><\/span>ohm, \u00e9 igual a<\/b><\/span><\/span><\/span><\/p>\n

<\/p>\n

<\/p>\n

17-(FUVEST-SP-018)<\/b><\/span><\/span><\/span><\/p>\n

<\/p>\n

<\/p>\n

18-(INSPER \u2013 SP \u2013 018)<\/b><\/span><\/span><\/span><\/p>\n

<\/p>\n

<\/p>\n

19-(UFPR-PR-018)<\/b><\/span><\/span><\/span><\/p>\n

<\/p>\n

O\u00a0<\/b><\/span><\/span><\/span>consumo el\u00e9trico<\/b><\/span><\/span><\/span>\u00a0de uma\u00a0<\/b><\/span><\/span><\/span>unidade residencial\u00a0<\/b><\/span><\/span><\/span>foi\u00a0<\/b><\/span><\/span><\/span>medido\u00a0<\/b><\/span><\/span><\/span>pelo seu propriet\u00e1rio, e o\u00a0<\/b><\/span><\/span><\/span>resultado obtido foi expresso pelo gr\u00e1fico ao lado,<\/b><\/span><\/span><\/span>\u00a0que descreve o\u00a0<\/b><\/span><\/span><\/span>consumo de corrente el\u00e9trica (i) da<\/b><\/span><\/span><\/span><\/p>\n

<\/p>\n

resid\u00eancia ao longo das 24 horas do dia (t).<\/b><\/span><\/span><\/span><\/p>\n

A\u00a0<\/b><\/span><\/span><\/span>unidade residencial\u00a0<\/b><\/span><\/span><\/span>\u00e9 alimentada por uma\u00a0<\/b><\/span><\/span><\/span>tens\u00e3o de 110 V.<\/b><\/span><\/span><\/span><\/p>\n

Considerando os\u00a0<\/b><\/span><\/span><\/span>dados expressos no gr\u00e1fico,\u00a0<\/b><\/span><\/span><\/span>assinale a\u00a0<\/b><\/span><\/span><\/span>alternativa que apresenta corretamente\u00a0<\/b><\/span><\/span><\/span>o\u00a0<\/b><\/span><\/span><\/span>valor da maior pot\u00eancia el\u00e9trica consumida ao longo do dia.<\/b><\/span><\/span><\/span><\/p>\n

<\/p>\n

20-(UEG \u2013 GO \u2013 2018)<\/b><\/span><\/span><\/span><\/p>\n

<\/p>\n

Uma pessoa utiliza um\u00a0<\/b><\/span><\/span><\/span>ferro el\u00e9trico de 1.000 W de pot\u00eancia, seis dias por semana, 30 min por dia.\u00a0<\/b><\/span><\/span><\/span>Qual ser\u00e1\u00a0<\/b><\/span><\/span><\/span>sua economia aproximada, em porcentagem,<\/b><\/span><\/span><\/span>\u00a0por semana, se\u00a0<\/b><\/span><\/span><\/span>passar a utilizar o ferro por 2 h e apenas um dia na semana?<\/b><\/span><\/span><\/span><\/p>\n

<\/p>\n

a) 22<\/b><\/span><\/span><\/span><\/p>\n

b) 33<\/b><\/span><\/span><\/span><\/p>\n

c) 44<\/b><\/span><\/span><\/span><\/p>\n

d) 55<\/b><\/span><\/span><\/span><\/p>\n

e) 66<\/b><\/span><\/span><\/span><\/p>\n

21-(Faculdade Pernambucana de Sa\u00fade \u2013 FPS \u2013 PE \u2013 018)<\/b><\/span><\/span><\/span><\/p>\n

<\/p>\n

<\/p>\n

<\/p>\n

A partir dos\u00a0<\/b><\/span><\/span><\/span>dados acima, determine o n\u00famero m\u00ednimo de pain\u00e9is, de 1,0 m2\u00a0de \u00e1rea cada, necess\u00e1rios para satisfazer seu consumo m\u00e9<\/b><\/span><\/span><\/span><\/p>\n

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

22-Universidade Estadual de Maring\u00e1\u00a0(UEM) \u2013 019<\/b><\/span><\/span><\/span><\/p>\n

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

Considere\u00a0<\/b><\/span><\/span><\/span>resistores cil\u00edndricos homog\u00eaneos de comprimento l, \u00e1rea A de se\u00e7\u00e3o transversal,\u00a0<\/b><\/span><\/span><\/span>feitos<\/b><\/span><\/span><\/span><\/p>\n

<\/p>\n

de um\u00a0<\/b><\/span><\/span><\/span>material cuja resistividade el\u00e9trica \u00e9 \u03c1. Assinale\u00a0<\/b><\/span><\/span><\/span>o que for\u00a0<\/b><\/span><\/span><\/span>correto.<\/b><\/span><\/span><\/span><\/p>\n

01)<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/span>A resist\u00eancia el\u00e9trica de cada um desses resistores \u00e9 diretamente proporcional ao comprimento l.<\/b><\/span><\/span><\/span><\/p>\n

02)<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/span>Quanto maior for a \u00e1rea A da se\u00e7\u00e3o transversal de um resistor, menor ser\u00e1 sua resist\u00eancia el\u00e9trica.<\/b><\/span><\/span><\/span><\/p>\n

04)<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/span>A resist\u00eancia el\u00e9trica oferecida por dois desses resistores ligados em s\u00e9rie \u00e9 equivalente \u00e0 resist\u00eancia oferecida por apenas um desses resistores com as mesmas caracter\u00edsticas, mas com o dobro do comprimento l.<\/b><\/span><\/span><\/span><\/p>\n

08)<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/span>A resist\u00eancia el\u00e9trica oferecida por dois desses resistores ligados em paralelo \u00e9 equivalente \u00e0 resist\u00eancia oferecida por apenas um desses resistores com as mesmas caracter\u00edsticas, mas com o dobro da \u00e1rea A da se\u00e7\u00e3o transversal.<\/b><\/span><\/span><\/span><\/p>\n

16)<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/span>No Sistema Internacional de Unidades (SI), a unidade de medida de resistividade el\u00e9trica \u00e9 \u2126\u00a0<\/b><\/span><\/span><\/span>\u22c5<\/b><\/span><\/span><\/span>m2<\/b><\/span><\/span><\/span><\/p>\n

23-(INSPER \u2013 SP \u2013 018)<\/b><\/span><\/span><\/span><\/p>\n

<\/p>\n

<\/p>\n

(A)\u00a0<\/b><\/span><\/span><\/span>baixas densidade e resistividade, e transportar alta corrente sob baixa tens\u00e3o.<\/b><\/span><\/span><\/span><\/p>\n

(B)\u00a0<\/b><\/span><\/span><\/span>baixa densidade com alta resistividade, e transportar baixa corrente sob baixa tens\u00e3o.<\/b><\/span><\/span><\/span><\/p>\n

(C)\u00a0<\/b><\/span><\/span><\/span>altas densidade e resistividade, e transportar qualquer corrente, mas sob baixa tens\u00e3o.<\/b><\/span><\/span><\/span><\/p>\n

(D)\u00a0<\/b><\/span><\/span><\/span>baixas densidade e resistividade, e transportar baixa corrente sob alta tens\u00e3o.<\/b><\/span><\/span><\/span><\/p>\n

(E)\u00a0<\/b><\/span><\/span><\/span>alta densidade com baixa resistividade, e transportar baixa corrente sob alta tens\u00e3o.<\/b><\/span><\/span><\/span><\/p>\n

24-(Faculdade de Tecnologia Termomec\u00e2nica \u2013 SP- 018)\u00a0<\/b><\/span><\/span><\/span><\/p>\n

<\/p>\n

<\/p>\n

25-(ESCOLA T\u00c9CNICA ESTADUAL \u2013 ETEC \u2013 SP \u2013 019)<\/b><\/span><\/span><\/span><\/p>\n

<\/p>\n

A\u00a0<\/b><\/span><\/span><\/span>resistencia el\u00e9trica e a capacidade de oposi\u00e7\u00e3o\u00a0<\/b><\/span><\/span><\/span>que um\u00a0<\/b><\/span><\/span><\/span>material oferece ao fluxo de corrente eletrica.<\/b><\/span><\/span><\/span><\/p>\n

A 2a\u00a0Lei de Ohm, com a qual podemos calcular o valor dessa resist\u00eancia el\u00e9trica, diz:<\/b><\/span><\/span><\/span><\/p>\n

\u201cA resist\u00eancia el\u00e9trica de um condutor de se\u00e7\u00e3o transversal constante \u00e9 diretamente proporcional ao seu comprimento e inversamente proporcional a \u00e1rea da sua se\u00e7\u00e3o transversal e depende do material desse condutor\u201d.<\/b><\/span><\/span><\/span><\/p>\n

Sua f\u00f3rmula \u00e9:<\/b><\/span><\/span><\/span><\/p>\n

<\/p>\n

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

R =\u00a0<\/b><\/span><\/span><\/span>Resistencia el\u00e9trica\u00a0<\/b><\/span><\/span><\/span>(\u03a9)<\/b><\/span><\/span><\/span><\/p>\n

\u03c1 =\u00a0<\/b><\/span><\/span><\/span>Resistividade do material\u00a0<\/b><\/span><\/span><\/span>(\u03a9 .m)<\/b><\/span><\/span><\/span><\/p>\n

L =\u00a0<\/b><\/span><\/span><\/span>Comprimento\u00a0<\/b><\/span><\/span><\/span>(m)<\/b><\/span><\/span><\/span><\/p>\n

A =\u00a0<\/b><\/span><\/span><\/span>Se\u00e7\u00e3o\u00a0<\/b><\/span><\/span><\/span>(m2)<\/b><\/span><\/span><\/span><\/p>\n

Um\u00a0<\/b><\/span><\/span><\/span>fio com \u03c1 = 2,8.10\u20138\u00a0\u03a9.m, comprimento de 1000 m e se\u00e7\u00e3o transversal de 2 mm2\u00a0tem uma<\/b><\/span><\/span><\/span><\/p>\n

resist\u00eancia el\u00e9trica com<\/b><\/span><\/span><\/span>\u00a0valor de<\/b><\/span><\/span><\/span><\/p>\n

(A)\u00a0<\/b><\/span><\/span><\/span>1 \u03a9.\u00a0<\/b><\/span><\/span><\/span>(B)\u00a0<\/b><\/span><\/span><\/span>2 \u03a9.\u00a0<\/b><\/span><\/span><\/span>(C)\u00a0<\/b><\/span><\/span><\/span>7 \u03a9.\u00a0<\/b><\/span><\/span><\/span>(D)\u00a0<\/b><\/span><\/span><\/span>14 \u03a9.\u00a0<\/b><\/span><\/span><\/span>(E)\u00a0<\/b><\/span><\/span><\/span>28 \u03a9.<\/b><\/span><\/span><\/span><\/p>\n

26-(Escola de Especialistas de Aeron\u00e1utica\u00a0\u2013\u00a0EEAR\u00a0\u2013 019\/020)<\/b><\/span><\/span><\/span><\/p>\n

<\/p>\n

O\u00a0<\/b><\/span><\/span><\/span>gr\u00e1fico a seguir corresponde ao comportamento da corrente el\u00e9trica\u00a0<\/b><\/span><\/span><\/span>que\u00a0<\/b><\/span><\/span><\/span>percorre um condutor, em fun\u00e7\u00e3o da diferen\u00e7a de potencial a ele aplicada.<\/b><\/span><\/span><\/span><\/p>\n

<\/p>\n

Sabendo-s<\/b><\/span><\/span><\/span>e que este condutor \u00e9\u00a0<\/b><\/span><\/span><\/span>constitu\u00eddo de um fio de 2m de comprimento e de um material cuja resistividade, a 20\u00b0C, vale 1,75. 10-6<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/span>\uf057<\/b><\/span><\/span><\/span>.m,<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/span>determine a \u00e1rea da se\u00e7\u00e3o transversal do fio e o valor da resist\u00eancia el\u00e9trica desse condutor na referida temperatura.<\/b><\/span><\/span><\/span><\/p>\n

a)\u00a0<\/b><\/span><\/span><\/span>0,7.10-4\u00a0cm2\u00a0e 0,5<\/b><\/span><\/span><\/span>\uf057<\/b><\/span><\/span><\/span><\/p>\n

b)\u00a0<\/b><\/span><\/span><\/span>0,7.10-4\u00a0cm2\u00a0e 500<\/b><\/span><\/span><\/span>\uf057<\/b><\/span><\/span><\/span><\/p>\n

c)\u00a0<\/b><\/span><\/span><\/span>0,83.10-4\u00a0cm2\u00a0e 12,5<\/b><\/span><\/span><\/span>\uf057<\/b><\/span><\/span><\/span><\/p>\n

d)\u00a0<\/b><\/span><\/span><\/span>0,83.10-4\u00a0cm2\u00a0e 500<\/b><\/span><\/span><\/span>\uf057<\/b><\/span><\/span><\/span><\/p>\n

C\u00e1lculo da resist\u00eancia do Resistor equivalente (R\u00ad<\/span><\/span><\/span>eq\u00ad<\/span><\/span><\/sub><\/span>)<\/span><\/span><\/span><\/p>\n

27-(PUC-SP-018)<\/b><\/span><\/span><\/span><\/p>\n

<\/p>\n

Determine, em ohm,\u00a0<\/b><\/span><\/span><\/span>o valor da\u00a0<\/b><\/span><\/span><\/span>resist\u00eancia do resistor equivalente<\/b><\/span><\/span><\/span>\u00a0da\u00a0<\/b><\/span><\/span><\/span>associa\u00e7\u00e3o\u00a0<\/b><\/span><\/span><\/span>abaixo:<\/b><\/span><\/span><\/span><\/p>\n

<\/p>\n

A)\u00a0<\/b><\/span><\/span><\/span>0\u00a0<\/b><\/span><\/span><\/span>B)\u00a0<\/b><\/span><\/span><\/span>12\u00a0<\/b><\/span><\/span><\/span>C)\u00a0<\/b><\/span><\/span><\/span>24\u00a0<\/b><\/span><\/span><\/span>D)\u00a0<\/b><\/span><\/span><\/span>36<\/b><\/span><\/span><\/span><\/p>\n

28-(Faculdade de Medicina de Jundia\u00ed \u201cFMJ\u201d \u2013SP \u2013 018)<\/b><\/span><\/span><\/span><\/p>\n

<\/p>\n

<\/p>\n

Caracter\u00edsticas das associa\u00e7\u00f5es s\u00e9rie e paralelo<\/span><\/span><\/span><\/p>\n

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29-(Faculdade de Ci\u00eancias M\u00e9dicas da Santa Casa de S\u00e3o Paulo \u2013 SP \u2013 019<\/b><\/span><\/span><\/span><\/span><\/span><\/p>\n

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<\/p>\n

<\/p>\n

30-Col\u00e9gio Naval 2018\/2019\u00a0<\/b><\/span><\/span><\/span><\/span><\/span><\/p>\n

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Um circuito el\u00e9trico \u00e9 composto por uma\u00a0<\/b><\/span><\/span>bateria ideal<\/b><\/span><\/span>\u00a0com uma\u00a0<\/b><\/span><\/span>tens\u00e3o (U) de 15 V<\/b><\/span><\/span>,\u00a0<\/b><\/span><\/span>resistores<\/b><\/span><\/span>\u00a0cada qual com uma\u00a0<\/b><\/span><\/span>resist\u00eancia el\u00e9trica (R) de 3 \u03a9<\/b><\/span><\/span>, fios condutores ideais e\u00a0<\/b><\/span><\/span>duas chaves (Ch)<\/b><\/span><\/span>\u00a0que permitem abrir ou fechar o circuito ou parte dele. Al\u00e9m disso, conta com um\u00a0<\/b><\/span><\/span>amper\u00edmetro ideal (A)<\/b><\/span><\/span>. Na situa\u00e7\u00e3o apresentada na figura abaixo, qual das op\u00e7\u00f5es fornece, respectivamente, a\u00a0<\/b><\/span><\/span>resist\u00eancia el\u00e9trica equivalente (Req)<\/b><\/span><\/span>\u00a0do circuito e a\u00a0<\/b><\/span><\/span>intensidade da corrente el\u00e9trica (I)<\/b><\/span><\/span>\u00a0indicada pelo amper\u00edmetro?<\/b><\/span><\/span><\/span><\/span><\/p>\n

<\/p>\n

(A) 1,0 \u03a9 e 30 A<\/b><\/span><\/span><\/span><\/span><\/p>\n

(B) 1,5 \u03a9 e 20 A<\/b><\/span><\/span><\/span><\/span><\/p>\n

(C) 1,5 \u03a9 e 10 A<\/b><\/span><\/span><\/span><\/span><\/p>\n

(D) 6,0 \u03a9 e 5,0 A<\/b><\/span><\/span><\/span><\/span><\/p>\n

(E) 9,0 \u03a9 e 3,3 A<\/b><\/span><\/span><\/span><\/span><\/p>\n

 <\/p>\n

31-(EsPCEx- AMAN \u2013 SP- RJ \u2013 2018\/19)<\/b><\/span><\/span><\/span><\/span><\/span><\/p>\n

<\/p>\n

No\u00a0<\/b><\/span><\/span>circuito desenhado abaixo,\u00a0<\/b><\/span><\/span>temos\u00a0<\/b><\/span><\/span>tr\u00eas pilhas ideais ligadas em paralelo que fornecem<\/b><\/span><\/span><\/span><\/span><\/p>\n

uma ddp igual a 25 V cada uma.\u00a0<\/b><\/span><\/span>Elas\u00a0<\/b><\/span><\/span>alimentam tr\u00eas resistores \u00f4hmicos: R1\u00a0= 10 \u03a9, R2\u00a0= R3= 20 \u03a9<\/b><\/span><\/span><\/span><\/span><\/p>\n

<\/p>\n

O amper\u00edmetro, o volt\u00edmetro\u00a0<\/b><\/span><\/span>e os\u00a0<\/b><\/span><\/span>fios condutores inseridos no circuito s\u00e3o todos ideais.\u00a0<\/b><\/span><\/span>As\u00a0<\/b><\/span><\/span>leituras<\/b><\/span><\/span><\/span><\/span><\/p>\n

indicadas no amper\u00edmetro (A) e no volt\u00edmetro (V) s\u00e3o<\/b><\/span><\/span>, respectivamente,<\/b><\/span><\/span><\/span><\/span><\/p>\n

[A]\u00a0<\/b><\/span><\/span>5,00 A e 25,00 V.<\/b><\/span><\/span><\/span><\/span><\/p>\n

[B]\u00a0<\/b><\/span><\/span>0,50 A e 20,00 V.<\/b><\/span><\/span><\/span><\/span><\/p>\n

[C]\u00a0<\/b><\/span><\/span>2,50 A e 16,66 V.<\/b><\/span><\/span><\/span><\/span><\/p>\n

[D]\u00a0<\/b><\/span><\/span>1,25 A e 12,50 V<\/b><\/span><\/span><\/span><\/span><\/p>\n

[E]\u00a0<\/b><\/span><\/span>3,75 A e 37,50 V.<\/b><\/span><\/span><\/span><\/span><\/p>\n

 <\/p>\n

32-(Faculdade de Medicina do ABC \u2013 FMABC \u2013 SP \u2013 019)<\/b><\/span><\/span><\/span><\/span><\/span><\/p>\n

<\/p>\n

A\u00a0<\/b><\/span><\/span>figura mostra um circuito el\u00e9trico\u00a0<\/b><\/span><\/span>constitu\u00eddo por\u00a0<\/b><\/span><\/span>tr\u00eas l\u00e2mpadas id\u00eanticas, um resistor \u00f4hmico e uma bateria ideal de for\u00e7a eletromotriz igual a 12 V.<\/b><\/span><\/span><\/span><\/span><\/p>\n

<\/p>\n

O\u00a0<\/b><\/span><\/span>gr\u00e1fico mostra a rela\u00e7\u00e3o entre a diferen\u00e7a de potencial aplicado aos terminais de cada l\u00e2mpada\u00a0<\/b><\/span><\/span>e a\u00a0<\/b><\/span><\/span>intensidade da corrente el\u00e9trica que a atravessa.<\/b><\/span><\/span><\/span><\/span><\/p>\n

Sabendo que a diferen\u00e7a de potencial entre os terminais do resistor \u00e9 de 3,0 V,\u00a0<\/b><\/span><\/span>sua\u00a0<\/b><\/span><\/span>resist\u00eancia el\u00e9trica\u00a0<\/b><\/span><\/span>\u00e9<\/b><\/span><\/span><\/span><\/span><\/p>\n

a)\u00a0<\/b><\/span><\/span>10,0\u00a0<\/b><\/span><\/span>b)\u00a0<\/b><\/span><\/span>14,3\u00a0<\/b><\/span><\/span>c)\u00a0<\/b><\/span><\/span>1,4\u00a0<\/b><\/span><\/span>d)\u00a0<\/b><\/span><\/span>3,0\u00a0<\/b><\/span><\/span>e)\u00a0<\/b><\/span><\/span>9,0<\/b><\/span><\/span><\/span><\/span><\/p>\n

 <\/p>\n

33-(Universidade Virtual do Estado de S\u00e3o Paulo \u2013 Univesp \u2013 2019)<\/b><\/span><\/span><\/span><\/p>\n

<\/p>\n

Cada vez mais, busca-se por equipamentos que consomem pouca energia el\u00e9trica.\u00a0<\/b><\/span><\/span><\/span>A\u00a0<\/b><\/span><\/span><\/span>passagem de corrente el\u00e9trica por um circuito pode promover o aquecimento de seus componentes, principalmente resistores.<\/b><\/span><\/span><\/span><\/p>\n

Esse aquecimento \u00e9 facilmente observado pela varia\u00e7\u00e3o da temperatura.<\/b><\/span><\/span><\/span><\/p>\n

Em\u00a0<\/b><\/span><\/span><\/span>alguns equipamentos, esse aquecimento \u00e9 bem-vindo (ferro de passar, torradeiras, chuveiros el\u00e9tricos etc.).<\/b><\/span><\/span><\/span><\/p>\n

Em outros, isso chega a ser prejudicial (computadores, tablets, celulares etc.).<\/b><\/span><\/span><\/span><\/p>\n

<\/p>\n

Considere o\u00a0<\/b><\/span><\/span><\/span>circuito el\u00e9trico esquem\u00e1tico da figura e as grandezas f\u00edsicas:<\/b><\/span><\/span><\/span><\/p>\n

<\/p>\n

\u2022\u00a0i\u00a0:\u00a0<\/b><\/span><\/span><\/span>intensidade de corrente el\u00e9trica;<\/b><\/span><\/span><\/span><\/p>\n

\u2022\u00a0U\u00a0:\u00a0<\/b><\/span><\/span><\/span>diferen\u00e7a de potencial el\u00e9trico (ddp) vari\u00e1vel;<\/b><\/span><\/span><\/span><\/p>\n

\u2022\u00a0R\u00a0:\u00a0<\/b><\/span><\/span><\/span>resist\u00eancia el\u00e9trica vari\u00e1vel;<\/b><\/span><\/span><\/span><\/p>\n

\u2022\u00a0P\u00a0:\u00a0<\/b><\/span><\/span><\/span>pot\u00eancia el\u00e9trica dissipada pelo resistor;<\/b><\/span><\/span><\/span><\/p>\n

\u2022\u00a0E\u00a0:\u00a0<\/b><\/span><\/span><\/span>quantidade de energia el\u00e9trica dissipada pelo resistor.<\/b><\/span><\/span><\/span><\/p>\n

Adotando a seguinte simbologia<\/b><\/span><\/span><\/span>:<\/b><\/span><\/span><\/span><\/p>\n

aumento<\/b><\/span><\/span><\/span>\u00a0do valor da grandeza:\u00a0<\/b><\/span><\/span><\/span><\/p>\n

decr\u00e9scimo<\/b><\/span><\/span><\/span>\u00a0do valor da grandeza:\u00a0<\/b><\/span><\/span><\/span><\/p>\n

manuten\u00e7\u00e3o\u00a0<\/b><\/span><\/span><\/span>do valor da grandeza (constante):\u00a0<\/b><\/span><\/span><\/span><\/p>\n

a rela\u00e7\u00e3o causal apresentada de forma correta, para o circuito el\u00e9trico esquem\u00e1tico na figura, \u00e9<\/b><\/span><\/span><\/span><\/p>\n

<\/p>\n

34-(UDESC-SC-019)<\/b><\/span><\/span><\/span><\/p>\n

<\/p>\n

Um\u00a0<\/b><\/span><\/span><\/span>resistor com resist\u00eancia de 10 \u2126\u00a0<\/b><\/span><\/span><\/span>\u00e9 ligado em\u00a0<\/b><\/span><\/span><\/span>paralelo com um resistor de resist\u00eancia de 40 \u2126.\u00a0<\/b><\/span><\/span><\/span>Uma\u00a0<\/b><\/span><\/span><\/span>fonte de tens\u00e3o de 12 V \u00e9 aplicada \u00e0 associa\u00e7\u00e3o.<\/b><\/span><\/span><\/span><\/p>\n

<\/p>\n

Assinale a alternativa que corresponde \u00e0 corrente el\u00e9trica total no circuito e \u00e0 pot\u00eancia dissipada no resistor de 40 \u2126 ,<\/b><\/span><\/span><\/span>\u00a0respectivamente.<\/b><\/span><\/span><\/span><\/p>\n

A.\u00a0<\/b><\/span><\/span><\/span>( ) 3,6A e 1,5W\u00a0<\/b><\/span><\/span><\/span>B.\u00a0<\/b><\/span><\/span><\/span>( ) 0,24A e 2,3W\u00a0<\/b><\/span><\/span><\/span>C.\u00a0<\/b><\/span><\/span><\/span>( ) 1,5A e 3,6W\u00a0<\/b><\/span><\/span><\/span>D.\u00a0<\/b><\/span><\/span><\/span>( ) 0,3A e 3,6W\u00a0<\/b><\/span><\/span><\/span>E.\u00a0<\/b><\/span><\/span><\/span>( ) 1,5A e 2,3W<\/b><\/span><\/span><\/span><\/p>\n

35-(Universidade Tecnol\u00f3gica Federal do Paran\u00e1\u00a0\u2013\u00a0UTFPR\u00a0\u2013 019)<\/b><\/span><\/span><\/span><\/p>\n

<\/p>\n

Tr\u00eas l\u00e2mpadas id\u00eanticas s\u00e3o instaladas em s\u00e9rie conforme figura abaixo:<\/b><\/span><\/span><\/span><\/p>\n

<\/p>\n

Sobre esta associa\u00e7\u00e3o \u00e9 correto afirmar que:<\/b><\/span><\/span><\/span><\/p>\n

A)\u00a0<\/b><\/span><\/span><\/span>a pot\u00eancia dissipada em cada l\u00e2mpada \u00e9 a mesma, consequentemente o brilho de cada l\u00e2mpada seria o mesmo se ela estivesse sozinha no circuito.<\/b><\/span><\/span><\/span><\/p>\n

B)\u00a0<\/b><\/span><\/span><\/span>a l\u00e2mpada 1 apresenta uma queda de tens\u00e3o maior do que a l\u00e2mpada 3.<\/b><\/span><\/span><\/span><\/p>\n

C)\u00a0<\/b><\/span><\/span><\/span>as tr\u00eas l\u00e2mpadas est\u00e3o associadas em s\u00e9rie. Este tipo de associa\u00e7\u00e3o \u00e9 utilizado para as l\u00e2mpadas das instala\u00e7\u00f5es residenciais.<\/b><\/span><\/span><\/span><\/p>\n

D)\u00a0<\/b><\/span><\/span><\/span>a corrente el\u00e9trica da l\u00e2mpada 3 \u00e9 maior que a da l\u00e2mpada 2.<\/b><\/span><\/span><\/span><\/p>\n

E)\u00a0<\/b><\/span><\/span><\/span>como a tens\u00e3o em cada l\u00e2mpada \u00e9\u00a0sempre menor que a dos terminais\u00a0da associa\u00e7\u00e3o, o brilho de cada l\u00e2mpada \u00e9 menor do que se ela estivesse sozinha no circuito.<\/b><\/span><\/span><\/span><\/p>\n

36-Universidade Estadual de Ci\u00eancias da Sa\u00fade de Alagoas (UNCISAL)\u00a0\u2013 2019<\/b><\/span><\/span><\/span><\/p>\n

<\/p>\n

Jos\u00e9\u00a0<\/b><\/span><\/span><\/span>disp\u00f5e de um ferro de passar roupas com as\u00a0<\/b><\/span><\/span><\/span>seguintes caracter\u00edsticas:\u00a0<\/b><\/span><\/span><\/span>tens\u00e3o de entrada (VF) de 110 V, corrente m\u00e1xima (Im\u00e1x) de 10 A\u00a0<\/b><\/span><\/span><\/span>e<\/b><\/span><\/span><\/span>\u00a0resist\u00eancia interna vari\u00e1vel RF<\/b><\/span><\/span><\/span>.<\/b><\/span><\/span><\/span><\/p>\n

A fim de\u00a0<\/b><\/span><\/span><\/span>utilizar o ferro em uma rede el\u00e9trica de 220 V,\u00a0<\/b><\/span><\/span><\/span>Jos\u00e9 decidiu\u00a0<\/b><\/span><\/span><\/span>inserir um circuito resistivo entre o ferro e a tomada,\u00a0<\/b><\/span><\/span><\/span>conforme ilustrado na<\/b><\/span><\/span><\/span>\u00a0figura abaixo, em que Req\u00a0\u00e9 a resist\u00eancia equivalente, que deve ser tamb\u00e9m vari\u00e1vel.<\/b><\/span><\/span><\/span>\u00a0A\u00a0<\/b><\/span><\/span><\/span>resist\u00eancia Req<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/span>deve ser\u00a0<\/b><\/span><\/span><\/span>dimensionada para que o ferro funcione conforme suas caracter\u00edsticas de tens\u00e3o VF\u00a0e sua corrente m\u00e1xima Im\u00e1x,\u00a0<\/b><\/span><\/span><\/span>ou seja, Jos\u00e9\u00a0<\/b><\/span><\/span><\/span>deve escolher o circuito que possibilite que o ferro, quando ligado, funcione com 110 V em sua entrada e sua corrente m\u00e1xima n\u00e3o seja ultrapassada.<\/b><\/span><\/span><\/span><\/p>\n

<\/p>\n

Qual circuito atende \u00e0 necessidade de Jos\u00e9?<\/b><\/span><\/span><\/span><\/p>\n

<\/p>\n

37-(UNICAMP-SP-018)<\/b><\/span><\/span><\/span><\/p>\n

<\/p>\n

Nos\u00a0<\/b><\/span><\/span><\/span>\u00faltimos anos, materiais ex\u00f3ticos\u00a0<\/b><\/span><\/span><\/span>conhecidos como\u00a0<\/b><\/span><\/span><\/span>isolantes topol\u00f3gicos\u00a0<\/b><\/span><\/span><\/span>se tornaram objeto de\u00a0<\/b><\/span><\/span><\/span>intensa investiga\u00e7\u00e3o cient\u00edfica\u00a0<\/b><\/span><\/span><\/span>em todo o\u00a0<\/b><\/span><\/span><\/span>mundo.<\/b><\/span><\/span><\/span><\/p>\n

<\/p>\n

38-(UNESP \u2013 SP \u2013 018)<\/b><\/span><\/span><\/span><\/p>\n

<\/p>\n

Em\u00a0<\/b><\/span><\/span><\/span>uma sala est\u00e3o ligados<\/b><\/span><\/span><\/span>\u00a0um\u00a0<\/b><\/span><\/span><\/span>aparelho de ar-condicionado,\u00a0<\/b><\/span><\/span><\/span>um\u00a0<\/b><\/span><\/span><\/span>televisor\u00a0<\/b><\/span><\/span><\/span>e\u00a0<\/b><\/span><\/span><\/span>duas l\u00e2mpadas id\u00eanticas,\u00a0<\/b><\/span><\/span><\/span>como mostra a\u00a0<\/b><\/span><\/span><\/span>figura.<\/b><\/span><\/span><\/span><\/p>\n

<\/p>\n

A\u00a0<\/b><\/span><\/span><\/span>tabela acima informa<\/b><\/span><\/span><\/span>\u00a0a\u00a0<\/b><\/span><\/span><\/span>pot\u00eancia e a diferen\u00e7a de potencial\u00a0<\/b><\/span><\/span><\/span>de funcionamento\u00a0<\/b><\/span><\/span><\/span>desses dispositivos.<\/b><\/span><\/span><\/span><\/p>\n

a) Considerando o custo de 1 kWh\u00a0<\/b><\/span><\/span><\/span>igual a\u00a0<\/b><\/span><\/span><\/span>R$ 0,30\u00a0<\/b><\/span><\/span><\/span>e os\u00a0<\/b><\/span><\/span><\/span>dados da tabela,\u00a0<\/b><\/span><\/span><\/span>calcule, em\u00a0<\/b><\/span><\/span><\/span>reais,<\/b><\/span><\/span><\/span>\u00a0o\u00a0<\/b><\/span><\/span><\/span>custo total da energia el\u00e9trica\u00a0<\/b><\/span><\/span><\/span>consumida pelos\u00a0<\/b><\/span><\/span><\/span>quatro dispositivos em um per\u00edodo de 5,0 horas.<\/b><\/span><\/span><\/span><\/p>\n

b) Considerando\u00a0<\/b><\/span><\/span><\/span>que os\u00a0<\/b><\/span><\/span><\/span>dispositivos\u00a0<\/b><\/span><\/span><\/span>estejam\u00a0<\/b><\/span><\/span><\/span>associados em paralelo\u00a0<\/b><\/span><\/span><\/span>e\u00a0<\/b><\/span><\/span><\/span>funcionando\u00a0<\/b><\/span><\/span><\/span>conforme as\u00a0<\/b><\/span><\/span><\/span>especifica\u00e7\u00f5es da tabela, calcule a intensidade da corrente el\u00e9trica total\u00a0<\/b><\/span><\/span><\/span>para esse conjunto<\/b><\/span><\/span><\/span>, em amp\u00e8res.<\/b><\/span><\/span><\/span><\/p>\n

39-(UFPR-PR-018)<\/b><\/span><\/span><\/span><\/p>\n

<\/p>\n

Na\u00a0<\/b><\/span><\/span><\/span>\u00e1rea de Eletrodin\u00e2mica,<\/b><\/span><\/span><\/span>\u00a0em\u00a0<\/b><\/span><\/span><\/span>circuitos el\u00e9tricos,\u00a0<\/b><\/span><\/span><\/span>s\u00e3o comuns\u00a0<\/b><\/span><\/span><\/span>associa\u00e7\u00f5es entre capacitores\u00a0<\/b><\/span><\/span><\/span>e<\/b><\/span><\/span><\/span><\/p>\n

<\/p>\n

entre\u00a0<\/b><\/span><\/span><\/span>resistores.<\/b><\/span><\/span><\/span><\/p>\n

A respeito do\u00a0<\/b><\/span><\/span><\/span>assunto,\u00a0<\/b><\/span><\/span><\/span>considere as\u00a0<\/b><\/span><\/span><\/span>seguintes afirmativas:<\/b><\/span><\/span><\/span><\/p>\n

1.\u00a0<\/b><\/span><\/span><\/span>Numa\u00a0<\/b><\/span><\/span><\/span>associa\u00e7\u00e3o de resistores em s\u00e9rie,\u00a0<\/b><\/span><\/span><\/span>o\u00a0<\/b><\/span><\/span><\/span>resistor equivalente\u00a0<\/b><\/span><\/span><\/span>sempre tem\u00a0<\/b><\/span><\/span><\/span>resist\u00eancia maior\u00a0<\/b><\/span><\/span><\/span>que\u00a0<\/b><\/span><\/span><\/span>qualquer uma das resist\u00eancias\u00a0<\/b><\/span><\/span><\/span>dos resistores que\u00a0<\/b><\/span><\/span><\/span>formam a associa\u00e7\u00e3o.<\/b><\/span><\/span><\/span><\/p>\n

2.\u00a0<\/b><\/span><\/span><\/span>Numa\u00a0<\/b><\/span><\/span><\/span>associa\u00e7\u00e3o de capacitores em paralelo,\u00a0<\/b><\/span><\/span><\/span>a\u00a0<\/b><\/span><\/span><\/span>tens\u00e3o\u00a0<\/b><\/span><\/span><\/span>aplicada ao\u00a0<\/b><\/span><\/span><\/span>capacitor equivalente\u00a0<\/b><\/span><\/span><\/span>\u00e9 dada pela\u00a0<\/b><\/span><\/span><\/span>soma das tens\u00f5es em cada capacitor<\/b><\/span><\/span><\/span>\u00a0que\u00a0<\/b><\/span><\/span><\/span>forma a associa\u00e7\u00e3o.<\/b><\/span><\/span><\/span><\/p>\n

3.\u00a0<\/b><\/span><\/span><\/span>Numa\u00a0<\/b><\/span><\/span><\/span>associa\u00e7\u00e3o de capacitores em s\u00e9rie,\u00a0<\/b><\/span><\/span><\/span>a\u00a0<\/b><\/span><\/span><\/span>carga<\/b><\/span><\/span><\/span>\u00a0em\u00a0<\/b><\/span><\/span><\/span>cada capacitor \u00e9 a mesma,\u00a0<\/b><\/span><\/span><\/span>e o\u00a0<\/b><\/span><\/span><\/span>capacitor equivalente tem uma carga igual<\/b><\/span><\/span><\/span>\u00a0\u00e0 de\u00a0<\/b><\/span><\/span><\/span>cada capacitor da associa\u00e7\u00e3o.<\/b><\/span><\/span><\/span><\/p>\n

Assinale a\u00a0<\/b><\/span><\/span><\/span>alternativa correta.<\/b><\/span><\/span><\/span><\/p>\n

a)\u00a0<\/b><\/span><\/span><\/span>Somente a\u00a0<\/b><\/span><\/span><\/span>afirmativa 1 \u00e9 verdadeira.<\/b><\/span><\/span><\/span><\/p>\n

b)\u00a0<\/b><\/span><\/span><\/span>Somente a\u00a0<\/b><\/span><\/span><\/span>afirmativa 2 \u00e9 verdadeira.<\/b><\/span><\/span><\/span><\/p>\n

c)\u00a0<\/b><\/span><\/span><\/span>Somente a\u00a0<\/b><\/span><\/span><\/span>afirmativa 3 \u00e9 verdadeira.<\/b><\/span><\/span><\/span><\/p>\n

d)\u00a0<\/b><\/span><\/span><\/span>Somente as\u00a0<\/b><\/span><\/span><\/span>afirmativas 1 e 2 s\u00e3o verdadeiras.<\/b><\/span><\/span><\/span><\/p>\n

e)\u00a0<\/b><\/span><\/span><\/span>Somente as\u00a0<\/b><\/span><\/span><\/span>afirmativas 1 e 3 s\u00e3o verdadeiras.<\/b><\/span><\/span><\/span><\/p>\n

Circuitos Simples com associa\u00e7\u00f5es mistas<\/b><\/span><\/span><\/span><\/p>\n

40-(Faculdade de Ci\u00eancias M\u00e9dicas da Santa Casa de S\u00e3o Paulo \u2013 SP \u2013 019<\/b><\/span><\/span><\/span><\/span><\/span><\/p>\n

<\/p>\n

<\/p>\n

<\/p>\n

 <\/p>\n

41-\u00a0Col\u00e9gio Naval 2018\/2019\u00a0<\/b><\/span><\/span><\/span><\/span><\/span><\/p>\n

<\/p>\n

Um circuito el\u00e9trico \u00e9 composto por uma\u00a0<\/b><\/span><\/span>bateria ideal<\/b><\/span><\/span>\u00a0com uma\u00a0<\/b><\/span><\/span>tens\u00e3o (U) de 15 V<\/b><\/span><\/span>,\u00a0<\/b><\/span><\/span>resistores<\/b><\/span><\/span>\u00a0cada qual com uma\u00a0<\/b><\/span><\/span>resist\u00eancia el\u00e9trica (R) de 3 \u03a9<\/b><\/span><\/span>, fios condutores ideais e\u00a0<\/b><\/span><\/span>duas chaves (Ch)<\/b><\/span><\/span>\u00a0que permitem abrir ou fechar o circuito ou parte dele. Al\u00e9m disso, conta com um\u00a0<\/b><\/span><\/span>amper\u00edmetro ideal (A)<\/b><\/span><\/span>. Na situa\u00e7\u00e3o apresentada na figura abaixo, qual das op\u00e7\u00f5es fornece, respectivamente, a\u00a0<\/b><\/span><\/span>resist\u00eancia el\u00e9trica equivalente (Req)<\/b><\/span><\/span>\u00a0do circuito e a\u00a0<\/b><\/span><\/span>intensidade da corrente el\u00e9trica (I)<\/b><\/span><\/span>\u00a0indicada pelo amper\u00edmetro?<\/b><\/span><\/span><\/span><\/span><\/p>\n

<\/p>\n

(A) 1,0 \u03a9 e 30 A<\/b><\/span><\/span><\/span><\/span><\/p>\n

(B) 1,5 \u03a9 e 20 A<\/b><\/span><\/span><\/span><\/span><\/p>\n

(C) 1,5 \u03a9 e 10 A<\/b><\/span><\/span><\/span><\/span><\/p>\n

(D) 6,0 \u03a9 e 5,0 A<\/b><\/span><\/span><\/span><\/span><\/p>\n

(E) 9,0 \u03a9 e 3,3 A<\/b><\/span><\/span><\/span><\/span><\/p>\n

42-Escola Naval 2018\/2019<\/b><\/span><\/span><\/span><\/span><\/span><\/p>\n

<\/p>\n

Analise a figura abaixo.<\/b><\/span><\/span><\/span><\/span><\/p>\n

<\/p>\n

Diferen\u00e7as de potencial de 30 volts j\u00e1 representam, para alguns indiv\u00edduos, risco de fibrila\u00e7\u00e3o induzida (mesmo que o choque el\u00e9trico seja de baixa corrente). Suponha que uma for\u00e7a eletromotriz aplicada entre as m\u00e3os de um ser humano seja, de modo simplificado, equivalente ao circuito mostrado na figura acima, com a magnitude da tens\u00e3o V0\u00a0no capacitor (cora\u00e7\u00e3o) determinando o grau de risco.\u00a0<\/b><\/span><\/span>Se a fem \u00e9 de 30 volts, a pot\u00eancia el\u00e9trica, em watts, dissipada no corpo humano \u00e9 igual a:<\/b><\/span><\/span><\/span><\/span><\/p>\n

(A) 0,9<\/b><\/span><\/span><\/span><\/span><\/p>\n

(B) 0,6<\/b><\/span><\/span><\/span><\/span><\/p>\n

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

(D) 0,3<\/b><\/span><\/span><\/span><\/span><\/p>\n

(E) 0,2<\/b><\/span><\/span><\/span><\/span><\/p>\n

 <\/p>\n

43-(EsPCEx- AMAN \u2013 SP- RJ \u2013 2018\/19)<\/b><\/span><\/span><\/span><\/span><\/span><\/p>\n

<\/p>\n

No\u00a0<\/b><\/span><\/span>circuito desenhado abaixo,\u00a0<\/b><\/span><\/span>temos\u00a0<\/b><\/span><\/span>tr\u00eas pilhas ideais ligadas em paralelo que fornecem<\/b><\/span><\/span><\/span><\/span><\/p>\n

uma ddp igual a 25 V cada uma.\u00a0<\/b><\/span><\/span>Elas\u00a0<\/b><\/span><\/span>alimentam tr\u00eas resistores \u00f4hmicos: R1\u00a0= 10 \u03a9, R2\u00a0= R3= 20 \u03a9<\/b><\/span><\/span><\/span><\/span><\/p>\n

<\/p>\n

O amper\u00edmetro, o volt\u00edmetro\u00a0<\/b><\/span><\/span>e os\u00a0<\/b><\/span><\/span>fios condutores inseridos no circuito s\u00e3o todos ideais.\u00a0<\/b><\/span><\/span>As\u00a0<\/b><\/span><\/span>leituras<\/b><\/span><\/span><\/span><\/span><\/p>\n

indicadas no amper\u00edmetro (A) e no volt\u00edmetro (V) s\u00e3o<\/b><\/span><\/span>, respectivamente,<\/b><\/span><\/span><\/span><\/span><\/p>\n

[A]\u00a0<\/b><\/span><\/span>5,00 A e 25,00 V.<\/b><\/span><\/span><\/span><\/span><\/p>\n

[B]\u00a0<\/b><\/span><\/span>0,50 A e 20,00 V.<\/b><\/span><\/span><\/span><\/span><\/p>\n

[C]\u00a0<\/b><\/span><\/span>2,50 A e 16,66 V.<\/b><\/span><\/span><\/span><\/span><\/p>\n

[D]\u00a0<\/b><\/span><\/span>1,25 A e 12,50 V<\/b><\/span><\/span><\/span><\/span><\/p>\n

[E]\u00a0<\/b><\/span><\/span>3,75 A e 37,50 V.<\/b><\/span><\/span><\/span><\/span><\/p>\n

 <\/p>\n

44-(Instituto Militar de Engenharia\u00a0\u2013\u00a0IME \u2013\u00a018\/19<\/b><\/span><\/span><\/span><\/span><\/span><\/p>\n

<\/p>\n

<\/p>\n

A figura mostra um circuito montado sob um plano inclinado feito de m<\/b><\/span><\/span>aterial condutor ideal, sem atrito de \u00e2ngulo \u03b1 com a horizontal.<\/b><\/span><\/span>\u00a0Um corpo \u00e9 liberado do ponto A e,\u00a0<\/b><\/span><\/span>\u00e0 medida que passa pelos sensores localizados nos pontos 1, 2, 3 e 4, as chaves Ch1, Ch2, Ch3\u00a0e Ch4\u00a0s\u00e3o fechadas instantaneamente.<\/b><\/span><\/span>\u00a0Diante do exposto,\u00a0<\/b><\/span><\/span>a energia el\u00e9trica dissipada durante a descida do corpo at\u00e9 o ponto B, em joules, \u00e9:<\/b><\/span><\/span><\/span><\/span><\/p>\n

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

\u2022\u00a0R1 = 10 \u03a9;<\/b><\/span><\/span><\/span><\/span><\/p>\n

\u2022\u00a0R2 = 10 \u03a9;<\/b><\/span><\/span><\/span><\/span><\/p>\n

\u2022\u00a0R3 = 5 \u03a9;<\/b><\/span><\/span><\/span><\/span><\/p>\n

\u2022\u00a0R4 = 2,5 \u03a9;<\/b><\/span><\/span><\/span><\/span><\/p>\n

\u2022\u00a0E = 10 V;<\/b><\/span><\/span><\/span><\/span><\/p>\n

\u2022\u00a0\u03b1 = 30\u00ba; e<\/b><\/span><\/span><\/span><\/span><\/p>\n

\u2022\u00a0g = 10 m\/s2.<\/b><\/span><\/span><\/span><\/span><\/p>\n

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

(B) 16<\/b><\/span><\/span><\/span><\/span><\/p>\n

(C) 32<\/b><\/span><\/span><\/span><\/span><\/p>\n

(D) 62<\/b><\/span><\/span><\/span><\/span><\/p>\n

(E) 120<\/b><\/span><\/span><\/span><\/span><\/p>\n

 <\/p>\n

45-(Faculdade de Medicina do ABC \u2013 FMABC \u2013 SP \u2013 019)<\/b><\/span><\/span><\/span><\/span><\/span><\/p>\n

<\/p>\n

A\u00a0<\/b><\/span><\/span>figura mostra um circuito el\u00e9trico\u00a0<\/b><\/span><\/span>constitu\u00eddo por\u00a0<\/b><\/span><\/span>tr\u00eas l\u00e2mpadas id\u00eanticas, um resistor \u00f4hmico e uma bateria ideal de for\u00e7a eletromotriz igual a 12 V.<\/b><\/span><\/span><\/span><\/span><\/p>\n

<\/p>\n

O\u00a0<\/b><\/span><\/span>gr\u00e1fico mostra a rela\u00e7\u00e3o entre a diferen\u00e7a de potencial aplicado aos terminais de cada l\u00e2mpada\u00a0<\/b><\/span><\/span>e a\u00a0<\/b><\/span><\/span>intensidade da corrente el\u00e9trica que a atravessa.<\/b><\/span><\/span><\/span><\/span><\/p>\n

Sabendo que a diferen\u00e7a de potencial entre os terminais do resistor \u00e9 de 3,0 V,\u00a0<\/b><\/span><\/span>sua\u00a0<\/b><\/span><\/span>resist\u00eancia el\u00e9trica\u00a0<\/b><\/span><\/span>\u00e9<\/b><\/span><\/span><\/span><\/span><\/p>\n

a)\u00a0<\/b><\/span><\/span>10,0\u00a0<\/b><\/span><\/span>b)\u00a0<\/b><\/span><\/span>14,3\u00a0<\/b><\/span><\/span>c)\u00a0<\/b><\/span><\/span>1,4\u00a0<\/b><\/span><\/span>d)\u00a0<\/b><\/span><\/span>3,0\u00a0<\/b><\/span><\/span>e)\u00a0<\/b><\/span><\/span>9,0<\/b><\/span><\/span><\/span><\/span><\/p>\n

46-(ESCOLA T\u00c9CNICA ESTADUAL \u2013 ETEC \u2013 SP \u2013 019)<\/b><\/span><\/span><\/span><\/p>\n

<\/p>\n

Um\u00a0<\/b><\/span><\/span><\/span>aluno de uma ETEC,<\/b><\/span><\/span><\/span>\u00a0durante um\u00a0<\/b><\/span><\/span><\/span>experimento em laborat\u00f3rio na escola, analisa um circuito<\/b><\/span><\/span><\/span><\/p>\n

que possui um conjunto de cinco resistores de 100 ohms associados em paralelo<\/b><\/span><\/span><\/span>\u00a0e\u00a0<\/b><\/span><\/span><\/span>ligados em<\/b><\/span><\/span><\/span><\/p>\n

<\/p>\n

um gerador de 24 volts que tamb\u00e9m est\u00e1 em paralelo com os resistores.<\/b><\/span><\/span><\/span><\/p>\n

Ao\u00a0<\/b><\/span><\/span><\/span>medir a tens\u00e3o no terceiro resistor, o valor\u00a0<\/b><\/span><\/span><\/span>ser\u00e1 de:<\/b><\/span><\/span><\/span><\/p>\n

(A)\u00a0<\/b><\/span><\/span><\/span>100 volts.\u00a0<\/b><\/span><\/span><\/span>(B)\u00a0<\/b><\/span><\/span><\/span>300 volts.\u00a0<\/b><\/span><\/span><\/span>(C)\u00a0<\/b><\/span><\/span><\/span>24 volts.\u00a0<\/b><\/span><\/span><\/span>(D)\u00a0<\/b><\/span><\/span><\/span>14,2 volts.\u00a0<\/b><\/span><\/span><\/span>(E)\u00a0<\/b><\/span><\/span><\/span>12 volts.<\/b><\/span><\/span><\/span><\/p>\n

47-(ESCOLA T\u00c9CNICA ESTADUAL \u2013 ETEC \u2013 SP \u2013 019)<\/b><\/span><\/span><\/span><\/p>\n

<\/p>\n

Em uma\u00a0<\/b><\/span><\/span><\/span>instala\u00e7\u00e3o el\u00e9trica, a fun\u00e7\u00e3o dos interruptores do tipo paralelo\u00a0<\/b><\/span><\/span><\/span>\u00e9:<\/b><\/span><\/span><\/span><\/p>\n

(A)\u00a0<\/b><\/span><\/span><\/span>Ligar e desligar duas l\u00e2mpadas, a partir de dois interruptores localizados no mesmo espelho,<\/b><\/span><\/span><\/span><\/p>\n

por possu\u00edrem duas se\u00e7\u00f5es.<\/b><\/span><\/span><\/span><\/p>\n

(B)\u00a0<\/b><\/span><\/span><\/span>Ligar e desligar uma l\u00e2mpada, a partir de um interruptor por possuir uma se\u00e7\u00e3o.<\/b><\/span><\/span><\/span><\/p>\n

(C)\u00a0<\/b><\/span><\/span><\/span>Exatamente a mesma fun\u00e7\u00e3o de um interruptor intermedi\u00e1rio.<\/b><\/span><\/span><\/span><\/p>\n

(D)\u00a0<\/b><\/span><\/span><\/span>Exatamente a mesma fun\u00e7\u00e3o de um interruptor simples.<\/b><\/span><\/span><\/span><\/p>\n

(E)\u00a0<\/b><\/span><\/span><\/span>Ligar e desligar uma l\u00e2mpada, a partir de dois interruptores localizados em pontos diferentes.<\/b><\/span><\/span><\/span><\/p>\n

48-(Universidade Virtual do Estado de S\u00e3o Paulo \u2013 Univesp \u2013 2019)<\/b><\/span><\/span><\/span><\/p>\n

<\/p>\n

Cada vez mais, busca-se por equipamentos que consomem pouca energia el\u00e9trica.\u00a0<\/b><\/span><\/span><\/span>A\u00a0<\/b><\/span><\/span><\/span>passagem de corrente el\u00e9trica por um circuito pode promover o aquecimento de seus componentes, principalmente resistores.<\/b><\/span><\/span><\/span><\/p>\n

Esse aquecimento \u00e9 facilmente observado pela varia\u00e7\u00e3o da temperatura.<\/b><\/span><\/span><\/span><\/p>\n

Em\u00a0<\/b><\/span><\/span><\/span>alguns equipamentos, esse aquecimento \u00e9 bem-vindo (ferro de passar, torradeiras, chuveiros el\u00e9tricos etc.).<\/b><\/span><\/span><\/span><\/p>\n

Em outros, isso chega a ser prejudicial (computadores, tablets, celulares etc.).<\/b><\/span><\/span><\/span><\/p>\n

<\/p>\n

Considere o\u00a0<\/b><\/span><\/span><\/span>circuito el\u00e9trico esquem\u00e1tico da figura e as grandezas f\u00edsicas:<\/b><\/span><\/span><\/span><\/p>\n

<\/p>\n

\u2022\u00a0i\u00a0:\u00a0<\/b><\/span><\/span><\/span>intensidade de corrente el\u00e9trica;<\/b><\/span><\/span><\/span><\/p>\n

\u2022\u00a0U\u00a0:\u00a0<\/b><\/span><\/span><\/span>diferen\u00e7a de potencial el\u00e9trico (ddp) vari\u00e1vel;<\/b><\/span><\/span><\/span><\/p>\n

\u2022\u00a0R\u00a0:\u00a0<\/b><\/span><\/span><\/span>resist\u00eancia el\u00e9trica vari\u00e1vel;<\/b><\/span><\/span><\/span><\/p>\n

\u2022\u00a0P\u00a0:\u00a0<\/b><\/span><\/span><\/span>pot\u00eancia el\u00e9trica dissipada pelo resistor;<\/b><\/span><\/span><\/span><\/p>\n

\u2022\u00a0E\u00a0:\u00a0<\/b><\/span><\/span><\/span>quantidade de energia el\u00e9trica dissipada pelo resistor.<\/b><\/span><\/span><\/span><\/p>\n

Adotando a seguinte simbologia<\/b><\/span><\/span><\/span>:<\/b><\/span><\/span><\/span><\/p>\n

aumento<\/b><\/span><\/span><\/span>\u00a0do valor da grandeza:\u00a0<\/b><\/span><\/span><\/span><\/p>\n

decr\u00e9scimo<\/b><\/span><\/span><\/span>\u00a0do valor da grandeza:\u00a0<\/b><\/span><\/span><\/span><\/p>\n

manuten\u00e7\u00e3o\u00a0<\/b><\/span><\/span><\/span>do valor da grandeza (constante):\u00a0<\/b><\/span><\/span><\/span><\/p>\n

a rela\u00e7\u00e3o causal apresentada de forma correta, para o circuito el\u00e9trico esquem\u00e1tico na figura, \u00e9<\/b><\/span><\/span><\/span><\/p>\n

<\/p>\n

49-(UDESC-SC-019)<\/b><\/span><\/span><\/span><\/p>\n

<\/p>\n

Um\u00a0<\/b><\/span><\/span><\/span>resistor com resist\u00eancia de 10 \u2126\u00a0<\/b><\/span><\/span><\/span>\u00e9 ligado em\u00a0<\/b><\/span><\/span><\/span>paralelo com um resistor de resist\u00eancia de 40 \u2126.\u00a0<\/b><\/span><\/span><\/span>Uma\u00a0<\/b><\/span><\/span><\/span>fonte de tens\u00e3o de 12 V \u00e9 aplicada \u00e0 associa\u00e7\u00e3o.<\/b><\/span><\/span><\/span><\/p>\n

<\/p>\n

Assinale a alternativa que corresponde \u00e0 corrente el\u00e9trica total no circuito e \u00e0 pot\u00eancia dissipada no resistor de 40 \u2126 ,<\/b><\/span><\/span><\/span>\u00a0respectivamente.<\/b><\/span><\/span><\/span><\/p>\n

A.\u00a0<\/b><\/span><\/span><\/span>( ) 3,6A e 1,5W\u00a0<\/b><\/span><\/span><\/span>B.\u00a0<\/b><\/span><\/span><\/span>( ) 0,24A e 2,3W\u00a0<\/b><\/span><\/span><\/span>C.\u00a0<\/b><\/span><\/span><\/span>( ) 1,5A e 3,6W\u00a0<\/b><\/span><\/span><\/span>D.\u00a0<\/b><\/span><\/span><\/span>( ) 0,3A e 3,6W\u00a0<\/b><\/span><\/span><\/span>E.\u00a0<\/b><\/span><\/span><\/span>( ) 1,5A e 2,3W<\/b><\/span><\/span><\/span><\/p>\n

50-(Universidade Estadual do Paran\u00e1\u00a0(UNESPAR) \u2013 019)<\/b><\/span><\/span><\/span><\/p>\n

<\/p>\n

O\u00a0<\/b><\/span><\/span><\/span>circuito abaixo representa uma associa\u00e7\u00e3o mista de resistores \u00f4hmicos alimentado\u00a0<\/b><\/span><\/span><\/span>por uma\u00a0<\/b><\/span><\/span><\/span>fonte de tens\u00e3o continua de 12V.\u00a0<\/b><\/span><\/span><\/span>Considerando\u00a0<\/b><\/span><\/span><\/span>R1\u00a0= R2\u00a0= 2 \u03a9, R3\u00a0= 1 \u03a9 e R4\u00a0= R5\u00a0= 3 \u03a9.<\/b><\/span><\/span><\/span><\/p>\n

<\/p>\n

Assinale a alternativa que mostra o valor da corrente i no circuito.<\/b><\/span><\/span><\/span><\/p>\n

a)\u00a0<\/b><\/span><\/span><\/span>4,8A;\u00a0<\/b><\/span><\/span><\/span>b)\u00a0<\/b><\/span><\/span><\/span>3A;\u00a0<\/b><\/span><\/span><\/span>c)\u00a0<\/b><\/span><\/span><\/span>2,8A;\u00a0<\/b><\/span><\/span><\/span>d)\u00a0<\/b><\/span><\/span><\/span>9A;\u00a0<\/b><\/span><\/span><\/span>e)\u00a0<\/b><\/span><\/span><\/span>1A.<\/b><\/span><\/span><\/span><\/p>\n

51-(Universidade Tecnol\u00f3gica Federal do Paran\u00e1\u00a0\u2013\u00a0UTFPR\u00a0\u2013 019)<\/b><\/span><\/span><\/span><\/p>\n

<\/p>\n

Tr\u00eas l\u00e2mpadas id\u00eanticas s\u00e3o instaladas em s\u00e9rie conforme figura abaixo:<\/b><\/span><\/span><\/span><\/p>\n

<\/p>\n

Sobre esta associa\u00e7\u00e3o \u00e9 correto afirmar que:<\/b><\/span><\/span><\/span><\/p>\n

A)\u00a0<\/b><\/span><\/span><\/span>a pot\u00eancia dissipada em cada l\u00e2mpada \u00e9 a mesma, consequentemente o brilho de cada l\u00e2mpada seria o mesmo se ela estivesse sozinha no circuito.<\/b><\/span><\/span><\/span><\/p>\n

B)\u00a0<\/b><\/span><\/span><\/span>a l\u00e2mpada 1 apresenta uma queda de tens\u00e3o maior do que a l\u00e2mpada 3.<\/b><\/span><\/span><\/span><\/p>\n

C)\u00a0<\/b><\/span><\/span><\/span>as tr\u00eas l\u00e2mpadas est\u00e3o associadas em s\u00e9rie. Este tipo de associa\u00e7\u00e3o \u00e9 utilizado para as l\u00e2mpadas das instala\u00e7\u00f5es residenciais.<\/b><\/span><\/span><\/span><\/p>\n

D)\u00a0<\/b><\/span><\/span><\/span>a corrente el\u00e9trica da l\u00e2mpada 3 \u00e9 maior que a da l\u00e2mpada 2.<\/b><\/span><\/span><\/span><\/p>\n

E)\u00a0<\/b><\/span><\/span><\/span>como a tens\u00e3o em cada l\u00e2mpada \u00e9\u00a0sempre menor que a dos terminais\u00a0da associa\u00e7\u00e3o, o brilho de cada l\u00e2mpada \u00e9 menor do que se ela estivesse sozinha no circuito.<\/b><\/span><\/span><\/span><\/p>\n

52-(UFRR-RR-019)<\/b><\/span><\/span><\/span><\/p>\n

<\/p>\n

Um\u00a0<\/b><\/span><\/span><\/span>estudante<\/b><\/span><\/span><\/span>\u00a0visando\u00a0<\/b><\/span><\/span><\/span>aumentar seus conhecimentos em eletricidade constr\u00f3i quatro circuitos<\/b><\/span><\/span><\/span><\/p>\n

<\/p>\n

el\u00e9tricos,<\/b><\/span><\/span><\/span>\u00a0utilizando\u00a0<\/b><\/span><\/span><\/span>quatro resistores de mesma resist\u00eancia R, conectados a uma fonte ideal de tens\u00e3o igual a\u00a0\u03b5,\u00a0<\/b><\/span><\/span><\/span>conforme descrito abaixo.<\/b><\/span><\/span><\/span><\/p>\n

Primeiro circuito<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/span>\u2013 O primeiro circuito\u00a0<\/b><\/span><\/span><\/span>\u00e9 constru\u00eddo ligando os quatro resistores em s\u00e9rie.<\/b><\/span><\/span><\/span><\/p>\n

Segundo circuito<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/span>\u2013 O segundo circuito\u00a0<\/b><\/span><\/span><\/span>\u00e9 constru\u00eddo ligando os quatro resistores em paralelo.\u00a0Terceiro circuito<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/span>\u2013 O terceiro circuito\u00a0<\/b><\/span><\/span><\/span>possui dois conjuntos de resistores. Cada conjunto \u00e9 formado por dois resistores conectados em paralelo. Em seguida, os dois conjuntos s\u00e3o conectados em s\u00e9rie.<\/b><\/span><\/span><\/span><\/p>\n

Quarto circuito\u00a0<\/b><\/span><\/span><\/span>\u2013 O estudante novamente\u00a0<\/b><\/span><\/span><\/span>forma dois conjuntos.\u00a0<\/b><\/span><\/span><\/span>Em um deles<\/b><\/span><\/span><\/span>, conecta dois resistores em paralelo e no outro, dois em s\u00e9rie.\u00a0<\/b><\/span><\/span><\/span>Em seguida\u00a0<\/b><\/span><\/span><\/span>liga os dois conjuntos em s\u00e9rie.<\/b><\/span><\/span><\/span>\u00a0Cada\u00a0<\/b><\/span><\/span><\/span>circuito \u00e9 alimentado por uma fonte ideal.<\/b><\/span><\/span><\/span><\/p>\n

Assinale\u00a0<\/b><\/span><\/span><\/span>a alternativa que\u00a0<\/b><\/span><\/span><\/span>apresenta os circuitos para os quais a fonte fornece uma corrente de 4\u03b5\/R e\u00a0\u03b5\/R respectivamente.<\/b><\/span><\/span><\/span><\/p>\n

A)\u00a0<\/b><\/span><\/span><\/span>Segundo e quarto circuitos;<\/b><\/span><\/span><\/span><\/p>\n

B)\u00a0<\/b><\/span><\/span><\/span>Terceiro e quarto circuitos;<\/b><\/span><\/span><\/span><\/p>\n

C)\u00a0<\/b><\/span><\/span><\/span>Segundo e terceiro circuitos;<\/b><\/span><\/span><\/span><\/p>\n

D)\u00a0<\/b><\/span><\/span><\/span>Primeiro e segundo circuitos;<\/b><\/span><\/span><\/span><\/p>\n

E)\u00a0<\/b><\/span><\/span><\/span>Primeiro e terceiro circuitos.<\/b><\/span><\/span><\/span><\/p>\n

53-(FPS-Faculdade Pernambucana de Sa\u00fade-PE-2019)<\/b><\/span><\/span><\/span><\/p>\n

<\/p>\n

<\/p>\n

54-Universidade Estadual de Ci\u00eancias da Sa\u00fade de Alagoas (UNCISAL)\u00a0\u2013 2019<\/b><\/span><\/span><\/span><\/p>\n

<\/p>\n

Jos\u00e9\u00a0<\/b><\/span><\/span><\/span>disp\u00f5e de um ferro de passar roupas com as\u00a0<\/b><\/span><\/span><\/span>seguintes caracter\u00edsticas:\u00a0<\/b><\/span><\/span><\/span>tens\u00e3o de entrada (VF) de 110 V, corrente m\u00e1xima (Im\u00e1x) de 10 A\u00a0<\/b><\/span><\/span><\/span>e<\/b><\/span><\/span><\/span>\u00a0resist\u00eancia interna vari\u00e1vel RF<\/b><\/span><\/span><\/span>.<\/b><\/span><\/span><\/span><\/p>\n

A fim de\u00a0<\/b><\/span><\/span><\/span>utilizar o ferro em uma rede el\u00e9trica de 220 V,\u00a0<\/b><\/span><\/span><\/span>Jos\u00e9 decidiu\u00a0<\/b><\/span><\/span><\/span>inserir um circuito resistivo entre o ferro e a tomada,\u00a0<\/b><\/span><\/span><\/span>conforme ilustrado na<\/b><\/span><\/span><\/span>\u00a0figura abaixo, em que Req\u00a0\u00e9 a resist\u00eancia equivalente, que deve ser tamb\u00e9m vari\u00e1vel.<\/b><\/span><\/span><\/span>\u00a0A\u00a0<\/b><\/span><\/span><\/span>resist\u00eancia Req<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/span>deve ser\u00a0<\/b><\/span><\/span><\/span>dimensionada para que o ferro funcione conforme suas caracter\u00edsticas de tens\u00e3o VF\u00a0e sua corrente m\u00e1xima Im\u00e1x,\u00a0<\/b><\/span><\/span><\/span>ou seja, Jos\u00e9\u00a0<\/b><\/span><\/span><\/span>deve escolher o circuito que possibilite que o ferro, quando ligado, funcione com 110 V em sua entrada e sua corrente m\u00e1xima n\u00e3o seja ultrapassada.<\/b><\/span><\/span><\/span><\/p>\n

<\/p>\n

Qual circuito atende \u00e0 necessidade de Jos\u00e9?<\/b><\/span><\/span><\/span><\/p>\n

<\/p>\n

55-(ENEM-MEC-017)<\/b><\/span><\/span><\/span><\/p>\n

<\/p>\n

<\/p>\n

56-ENCCEJA (Exame para Certifica\u00e7\u00e3o de Compet\u00eancias de Jovens e Adultos \u2013 INEP \u2013 2017)<\/b><\/span><\/span><\/span><\/p>\n

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

A\u00a0<\/b><\/span><\/span><\/span>figura apresenta o esquema el\u00e9trico\u00a0<\/b><\/span><\/span><\/span>do\u00a0<\/b><\/span><\/span><\/span>painel luminoso de uma vitrine.<\/b><\/span><\/span><\/span><\/p>\n

Um\u00a0<\/b><\/span><\/span><\/span>t\u00e9cnico deseja trocar as duas l\u00e2mpadas\u00a0<\/b><\/span><\/span><\/span>ligadas em\u00a0<\/b><\/span><\/span><\/span>paralelo por uma \u00fanica l\u00e2mpada,\u00a0<\/b><\/span><\/span><\/span>de modo que, com o\u00a0<\/b><\/span><\/span><\/span>circuito fechado, a corrente na bateria seja a mesma.<\/b><\/span><\/span><\/span><\/p>\n

<\/p>\n

Para que\u00a0<\/b><\/span><\/span><\/span>isso ocorra,\u00a0<\/b><\/span><\/span><\/span>a\u00a0<\/b><\/span><\/span><\/span>nova l\u00e2mpada deve ter resist\u00eancia el\u00e9trica,\u00a0<\/b><\/span><\/span><\/span>em\u00a0<\/b><\/span><\/span><\/span>ohm,\u00a0<\/b><\/span><\/span><\/span>de<\/b><\/span><\/span><\/span><\/p>\n

<\/p>\n

57-(FUVEST-SP-018)<\/b><\/span><\/span><\/span><\/p>\n

<\/p>\n

Atualmente\u00a0<\/b><\/span><\/span><\/span>s\u00e3o usados\u00a0<\/b><\/span><\/span><\/span>LEDs (Light Emitting Diode)\u00a0<\/b><\/span><\/span><\/span>na\u00a0<\/b><\/span><\/span><\/span>ilumina\u00e7\u00e3o dom\u00e9stica.<\/b><\/span><\/span><\/span><\/p>\n

LEDs s\u00e3o dispositivos semicondutores\u00a0<\/b><\/span><\/span><\/span>que\u00a0<\/b><\/span><\/span><\/span>conduzem a corrente el\u00e9trica apenas em um sentido.<\/b><\/span><\/span><\/span><\/p>\n

Na\u00a0<\/b><\/span><\/span><\/span>figura,<\/b><\/span><\/span><\/span>\u00a0h\u00e1 um\u00a0<\/b><\/span><\/span><\/span>circuito de alimenta\u00e7\u00e3o de um LED (L) de 8 W,\u00a0<\/b><\/span><\/span><\/span>que\u00a0<\/b><\/span><\/span><\/span>opera<\/b><\/span><\/span><\/span>\u00a0com\u00a0<\/b><\/span><\/span><\/span>4 V,\u00a0<\/b><\/span><\/span><\/span>sendo\u00a0<\/b><\/span><\/span><\/span>alimentado por uma fonte (F) de 6 V.<\/b><\/span><\/span><\/span><\/p>\n

<\/p>\n

O\u00a0<\/b><\/span><\/span><\/span>valor da resist\u00eancia do resistor (R), em \u2126, necess\u00e1rio\u00a0<\/b><\/span><\/span><\/span>para que o\u00a0<\/b><\/span><\/span><\/span>LED opere com seus valores nominais<\/b><\/span><\/span><\/span>\u00a0\u00e9, aproximadamente,<\/b><\/span><\/span><\/span><\/p>\n

<\/p>\n

58-(UNICAMP-SP-018)<\/b><\/span><\/span><\/span><\/p>\n

<\/p>\n

Nos\u00a0<\/b><\/span><\/span><\/span>\u00faltimos anos, materiais ex\u00f3ticos\u00a0<\/b><\/span><\/span><\/span>conhecidos como\u00a0<\/b><\/span><\/span><\/span>isolantes topol\u00f3gicos\u00a0<\/b><\/span><\/span><\/span>se tornaram objeto de\u00a0<\/b><\/span><\/span><\/span>intensa investiga\u00e7\u00e3o cient\u00edfica\u00a0<\/b><\/span><\/span><\/span>em todo o\u00a0<\/b><\/span><\/span><\/span>mundo.<\/b><\/span><\/span><\/span><\/p>\n

<\/p>\n

59-(Faculdade de Ci\u00eancias M\u00e9dicas da Santa Casa de S\u00e3o Paulo \u2013 018)<\/b><\/span><\/span><\/span><\/p>\n

<\/p>\n

<\/p>\n

60-(Faculdade de Medicina de Jundia\u00ed \u201cFMJ\u201d \u2013SP \u2013 018)<\/b><\/span><\/span><\/span><\/p>\n

<\/p>\n

<\/p>\n

61-UERJ-019<\/b><\/span><\/span><\/span><\/p>\n

<\/p>\n

Resistores \u00f4hmicos\u00a0<\/b><\/span><\/span><\/span>id\u00eanticos<\/b><\/span><\/span><\/span>\u00a0foram associados em quatro circuitos distintos e submetidos \u00e0\u00a0<\/b><\/span><\/span><\/span>mesma tens\u00e3o UA,B<\/b><\/span><\/span><\/span>. Observe os esquemas:<\/b><\/span><\/span><\/span><\/p>\n


\n<\/b><\/span><\/span><\/span>Nessas condi\u00e7\u00f5es,\u00a0<\/b><\/span><\/span><\/span>a corrente el\u00e9trica<\/b><\/span><\/span><\/span>\u00a0de\u00a0<\/b><\/span><\/span><\/span>menor intensidade<\/b><\/span><\/span><\/span>\u00a0se estabelece no seguinte circuito:<\/b><\/span><\/span><\/span><\/p>\n

(A) I<\/b><\/span><\/span><\/span><\/p>\n

(B) II<\/b><\/span><\/span><\/span><\/p>\n

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

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

Equa\u00e7\u00e3o do Gerador<\/span><\/span><\/span><\/p>\n

62-(Faculdade de Ci\u00eancias M\u00e9dicas da Santa Casa de S\u00e3o Paulo \u2013 018)<\/b><\/span><\/span><\/span><\/p>\n

<\/p>\n

<\/p>\n

63-(FAMERP-SP-018)<\/b><\/span><\/span><\/span><\/p>\n

<\/p>\n

<\/p>\n

64-(ENEM-MEC-017)<\/b><\/span><\/span><\/span><\/p>\n

<\/p>\n

<\/p>\n

65-(ESCOLA T\u00c9CNICA ESTADUAL \u2013 ETEC \u2013 SP \u2013 019)<\/b><\/span><\/span><\/span><\/p>\n

<\/p>\n

No\u00a0<\/b><\/span><\/span><\/span>estudo da eletricidade, iniciam-se os estudos, considerando a condi\u00e7\u00e3o ideal para depois estudar<\/b><\/span><\/span><\/span><\/p>\n

a condi\u00e7\u00e3o real.<\/b><\/span><\/span><\/span>\u00a0A\u00a0<\/b><\/span><\/span><\/span>reta da curva caracter\u00edstica de um gerador el\u00e9trico real pode ser desenhada<\/b><\/span><\/span><\/span><\/p>\n

utilizando-se os pontos<\/b><\/span><\/span><\/span><\/p>\n

(A)\u00a0<\/b><\/span><\/span><\/span>A for\u00e7a eletromotriz (Fem) em Volts e a corrente de curto circuito (icc) em Amperes<\/b><\/span><\/span><\/span><\/p>\n

(B)\u00a0<\/b><\/span><\/span><\/span>A for\u00e7a eletromotriz (Fem) em Volts e a resist\u00eancia interna (r.i.) em Ohms<\/b><\/span><\/span><\/span><\/p>\n

(C)\u00a0<\/b><\/span><\/span><\/span>Resist\u00eancia interna (r.i.) em Ohms e a corrente de curto circuito (icc) em Amperes<\/b><\/span><\/span><\/span><\/p>\n

(D)\u00a0<\/b><\/span><\/span><\/span>Tens\u00e3o \u00fatil do gerador e a resist\u00eancia interna (r.i.) em Ohms<\/b><\/span><\/span><\/span><\/p>\n

(E)\u00a0<\/b><\/span><\/span><\/span>A corrente de curto circuito (icc) em Amperes e a pot\u00eancia total em Watts<\/b><\/span><\/span><\/span><\/p>\n

66-(Faculdade de Medicina de Taubat\u00e9 \u2013 FMT \u2013 019)<\/b><\/span><\/span><\/span><\/p>\n

<\/p>\n

Considere o circuito representado abaixo. Ap\u00f3s fecharmos a chave faca F, o gerador n\u00e3o ideal alimenta o resistor R1\u00a0de 100 ohms.<\/b><\/span><\/span><\/span><\/p>\n

<\/p>\n

Sabendo que a\u00a0<\/b><\/span><\/span><\/span>resist\u00eancia interna do gerador \u00e9 de r = 20 ohms,<\/b><\/span><\/span><\/span>\u00a0e que a\u00a0<\/b><\/span><\/span><\/span>for\u00e7a eletromotriz do gerador \u00e9 de 120 volts,<\/b><\/span><\/span><\/span>\u00a0a\u00a0<\/b><\/span><\/span><\/span>pot\u00eancia dissipada no gerador, medida em watts,\u00a0<\/b><\/span><\/span><\/span>\u00e9 de<\/b><\/span><\/span><\/span><\/p>\n

a)\u00a0<\/b><\/span><\/span><\/span>100\u00a0<\/b><\/span><\/span><\/span>b)\u00a0<\/b><\/span><\/span><\/span>50\u00a0<\/b><\/span><\/span><\/span>c)\u00a0<\/b><\/span><\/span><\/span>40\u00a0<\/b><\/span><\/span><\/span>d)\u00a0<\/b><\/span><\/span><\/span>30\u00a0<\/b><\/span><\/span><\/span>e)\u00a0<\/b><\/span><\/span><\/span>20<\/b><\/span><\/span><\/span><\/p>\n

Aparelhos de medi\u00e7\u00e3o el\u00e9trica<\/b><\/span><\/span><\/span><\/p>\n

67-(FGV-RJ-019)<\/b><\/span><\/span><\/span><\/p>\n

<\/p>\n

<\/p>\n

<\/p>\n

68-(UNESP-SP-018)<\/b><\/span><\/span><\/span><\/p>\n

<\/p>\n

Para\u00a0<\/b><\/span><\/span><\/span>obter experimentalmente\u00a0<\/b><\/span><\/span><\/span>a curva da\u00a0<\/b><\/span><\/span><\/span>diferen\u00e7a de potencial U<\/b><\/span><\/span><\/span>\u00a0em\u00a0<\/b><\/span><\/span><\/span>fun\u00e7\u00e3o da intensidade da corrente el\u00e9trica i\u00a0<\/b><\/span><\/span><\/span>para uma\u00a0<\/b><\/span><\/span><\/span>l\u00e2mpada, um aluno montou o circuito a seguir.<\/b><\/span><\/span><\/span><\/p>\n

Colocando<\/b><\/span><\/span><\/span>\u00a0entre os pontos\u00a0<\/b><\/span><\/span><\/span>A e B resistores com diversos valores de resist\u00eancia,<\/b><\/span><\/span><\/span>\u00a0ele obteve\u00a0<\/b><\/span><\/span><\/span>diferentes valores de U\u00a0<\/b><\/span><\/span><\/span>e de\u00a0<\/b><\/span><\/span><\/span>i para a l\u00e2mpada.<\/b><\/span><\/span><\/span><\/p>\n

<\/p>\n

Considerando que a\u00a0<\/b><\/span><\/span><\/span>bateria de 9,0 V, os aparelhos de medida e os fios de liga\u00e7\u00e3o sejam ideais,<\/b><\/span><\/span><\/span><\/p>\n

quando o\u00a0<\/b><\/span><\/span><\/span>aluno obteve as medidas U = 5,70 V e i = 0,15 A,\u00a0<\/b><\/span><\/span><\/span>a\u00a0<\/b><\/span><\/span><\/span>resist\u00eancia do resistor\u00a0<\/b><\/span><\/span><\/span>colocado\u00a0<\/b><\/span><\/span><\/span>entre\u00a0<\/b><\/span><\/span><\/span>os\u00a0<\/b><\/span><\/span><\/span>pontos A e B era de<\/b><\/span><\/span><\/span><\/p>\n

<\/p>\n

69-(PUC \u2013 RIO \u2013 019)<\/b><\/span><\/span><\/span><\/p>\n

<\/p>\n

Uma\u00a0<\/b><\/span><\/span><\/span>bateria fornece uma voltagem VB\u00a0e possui uma resist\u00eancia interna r.<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/span>Colocando a bateria em contato com um volt\u00edmetro, a medida \u00e9 12 V<\/b><\/span><\/span><\/span>. Colocando a seguir\u00a0<\/b><\/span><\/span><\/span>um amper\u00edmetro em s\u00e9rie com a bateria e com um resistor R = 1,0 k\u03a9, a medida \u00e9 8 mA.<\/b><\/span><\/span><\/span><\/p>\n

<\/p>\n

A\u00a0<\/b><\/span><\/span><\/span>partir dessas medidas, os valores da voltagem VB\u00a0e da resist\u00eancia interna r, em V e k\u03a9, s\u00e3o<\/b><\/span><\/span><\/span>\u00a0respectivamente:<\/b><\/span><\/span><\/span><\/p>\n

A)\u00a0<\/b><\/span><\/span><\/span>12 e 0,50<\/b><\/span><\/span><\/span><\/p>\n

B)\u00a0<\/b><\/span><\/span><\/span>24 e 1,0<\/b><\/span><\/span><\/span><\/p>\n

C)\u00a0<\/b><\/span><\/span><\/span>12 e 1,0<\/b><\/span><\/span><\/span><\/p>\n

D)\u00a0<\/b><\/span><\/span><\/span>24 e 0,50<\/b><\/span><\/span><\/span><\/p>\n

E)\u00a0<\/b><\/span><\/span><\/span>12 e 2,0<\/b><\/span><\/span><\/span><\/p>\n

70-(ENEM-MEC-017)<\/b><\/span><\/span><\/span><\/p>\n

<\/p>\n

<\/p>\n

71-(EsPCEx- AMAN \u2013 SP- RJ \u2013 2018\/19)<\/b><\/span><\/span><\/span><\/span><\/span><\/p>\n

<\/p>\n

No\u00a0<\/b><\/span><\/span>circuito desenhado abaixo,\u00a0<\/b><\/span><\/span>temos\u00a0<\/b><\/span><\/span>tr\u00eas pilhas ideais ligadas em paralelo que fornecem<\/b><\/span><\/span><\/span><\/span><\/p>\n

uma ddp igual a 25 V cada uma.\u00a0<\/b><\/span><\/span>Elas\u00a0<\/b><\/span><\/span>alimentam tr\u00eas resistores \u00f4hmicos: R1\u00a0= 10 \u03a9, R2\u00a0= R3= 20 \u03a9<\/b><\/span><\/span><\/span><\/span><\/p>\n

<\/p>\n

O amper\u00edmetro, o volt\u00edmetro\u00a0<\/b><\/span><\/span>e os\u00a0<\/b><\/span><\/span>fios condutores inseridos no circuito s\u00e3o todos ideais.\u00a0<\/b><\/span><\/span>As\u00a0<\/b><\/span><\/span>leituras<\/b><\/span><\/span><\/span><\/span><\/p>\n

indicadas no amper\u00edmetro (A) e no volt\u00edmetro (V) s\u00e3o<\/b><\/span><\/span>, respectivamente,<\/b><\/span><\/span><\/span><\/span><\/p>\n

[A]\u00a0<\/b><\/span><\/span>5,00 A e 25,00 V.<\/b><\/span><\/span><\/span><\/span><\/p>\n

[B]\u00a0<\/b><\/span><\/span>0,50 A e 20,00 V.<\/b><\/span><\/span><\/span><\/span><\/p>\n

[C]\u00a0<\/b><\/span><\/span>2,50 A e 16,66 V.<\/b><\/span><\/span><\/span><\/span><\/p>\n

[D]\u00a0<\/b><\/span><\/span>1,25 A e 12,50 V<\/b><\/span><\/span><\/span><\/span><\/p>\n

[E]\u00a0<\/b><\/span><\/span>3,75 A e 37,50 V.<\/b><\/span><\/span><\/span><\/span><\/p>\n

72-Escola Naval 2018\/2019<\/b><\/span><\/span><\/span><\/span><\/span><\/p>\n

<\/p>\n

Analise a figura abaixo.<\/b><\/span><\/span><\/span><\/span><\/p>\n

<\/p>\n

Para que um galvan\u00f4metro ideal G (resist\u00eancia nula), o qual suporta uma corrente m\u00e1xima lGm. seja utilizado em um simples amper\u00edmetro capaz de indicar qualquer valor de corrente, s\u00e3o utilizadas as resist\u00eancias Rs\u00a0(shunt, em paralelo com G) e RG\u00a0(em s\u00e9rie com G), como mostra o circuito da figura acima.\u00a0<\/b><\/span><\/span>Considere que, medindo uma corrente I=50,5 A utilizando esse amper\u00edmetro, o galvan\u00f4metro apresenta sua deflex\u00e3o m\u00e1xima indicando 50,0 A, com lG=lGm=500mA.\u00a0<\/b><\/span><\/span>Sendo assim,\u00a0<\/b><\/span><\/span>a raz\u00e3o RG\/RS<\/b><\/span><\/span>\u00a0<\/b><\/span><\/span>utilizada nessa medida vale:<\/b><\/span><\/span><\/span><\/span><\/p>\n

(A) 15,0<\/b><\/span><\/span><\/span><\/span><\/p>\n

(B) 30,0<\/b><\/span><\/span><\/span><\/span><\/p>\n

(C) 75,0<\/b><\/span><\/span><\/span><\/span><\/p>\n

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

(E) 150<\/b><\/span><\/span><\/span><\/span><\/p>\n

\u00a073-Col\u00e9gio Naval 2018\/2019\u00a0<\/b><\/span><\/span><\/span><\/span><\/span><\/p>\n

<\/p>\n

Um circuito el\u00e9trico \u00e9 composto por uma\u00a0<\/b><\/span><\/span>bateria ideal<\/b><\/span><\/span>\u00a0com uma\u00a0<\/b><\/span><\/span>tens\u00e3o (U) de 15 V<\/b><\/span><\/span>,\u00a0<\/b><\/span><\/span>resistores<\/b><\/span><\/span>\u00a0cada qual com uma\u00a0<\/b><\/span><\/span>resist\u00eancia el\u00e9trica (R) de 3 \u03a9<\/b><\/span><\/span>, fios condutores ideais e\u00a0<\/b><\/span><\/span>duas chaves (Ch)<\/b><\/span><\/span>\u00a0que permitem abrir ou fechar o circuito ou parte dele. Al\u00e9m disso, conta com um\u00a0<\/b><\/span><\/span>amper\u00edmetro ideal (A)<\/b><\/span><\/span>. Na situa\u00e7\u00e3o apresentada na figura abaixo, qual das op\u00e7\u00f5es fornece, respectivamente, a\u00a0<\/b><\/span><\/span>resist\u00eancia el\u00e9trica equivalente (Req)<\/b><\/span><\/span>\u00a0do circuito e a\u00a0<\/b><\/span><\/span>intensidade da corrente el\u00e9trica (I)<\/b><\/span><\/span>\u00a0indicada pelo amper\u00edmetro?<\/b><\/span><\/span><\/span><\/span><\/p>\n

<\/p>\n

(A) 1,0 \u03a9 e 30 A<\/b><\/span><\/span><\/span><\/span><\/p>\n

(B) 1,5 \u03a9 e 20 A<\/b><\/span><\/span><\/span><\/span><\/p>\n

(C) 1,5 \u03a9 e 10 A<\/b><\/span><\/span><\/span><\/span><\/p>\n

(D) 6,0 \u03a9 e 5,0 A<\/b><\/span><\/span><\/span><\/span><\/p>\n

(E) 9,0 \u03a9 e 3,3 A<\/b><\/span><\/span><\/span><\/span><\/p>\n

Circuitos compostos<\/span><\/span><\/span><\/p>\n

74-(Faculdade de Tecnologia Termomec\u00e2nica \u2013 SP- 019)<\/b><\/span><\/span><\/span><\/span><\/span><\/p>\n

<\/p>\n

A\u00a0<\/b><\/span><\/span>figura mostra um circuito el\u00e9trico<\/b><\/span><\/span>\u00a0formado por\u00a0<\/b><\/span><\/span>duas malhas, havendo um gerador el\u00e9trico em cada uma.<\/b><\/span><\/span><\/span><\/span><\/p>\n

<\/p>\n

Sabendo que\u00a0<\/b><\/span><\/span>as setas indicam os sentidos reais das correntes el\u00e9tricas nestes ramos,\u00a0<\/b><\/span><\/span>a\u00a0<\/b><\/span><\/span>alternativa que apresenta os valores corretos de I, R e U, respectivamente,\u00a0<\/b><\/span><\/span>\u00e9<\/b><\/span><\/span><\/span><\/span><\/p>\n

(A)\u00a0<\/b><\/span><\/span>5 A ; 1,0 \u03a9 ; 12 V.<\/b><\/span><\/span><\/span><\/span><\/p>\n

(B)\u00a0<\/b><\/span><\/span>5 A ; 1,2 \u03a9 ; 14 V.<\/b><\/span><\/span><\/span><\/span><\/p>\n

(C)\u00a0<\/b><\/span><\/span>8 A ; 1,0 \u03a9 ; 10 V.<\/b><\/span><\/span><\/span><\/span><\/p>\n

(D)\u00a0<\/b><\/span><\/span>8 A ; 0,5 \u03a9 ; 22 V.<\/b><\/span><\/span><\/span><\/span><\/p>\n

(E)\u00a0<\/b><\/span><\/span>10 A ; 5 \u03a9 ; 9 V<\/b><\/span><\/span><\/span><\/span><\/p>\n

75-(ESCOLA T\u00c9CNICA ESTADUAL \u2013 ETEC \u2013 SP \u2013 019)<\/b><\/span><\/span><\/span><\/p>\n

<\/p>\n

Em uma\u00a0<\/b><\/span><\/span><\/span>instala\u00e7\u00e3o el\u00e9trica, a fun\u00e7\u00e3o dos interruptores do tipo paralelo\u00a0<\/b><\/span><\/span><\/span>\u00e9:<\/b><\/span><\/span><\/span><\/p>\n

(A)\u00a0<\/b><\/span><\/span><\/span>Ligar e desligar duas l\u00e2mpadas, a partir de dois interruptores localizados no mesmo espelho,<\/b><\/span><\/span><\/span><\/p>\n

por possu\u00edrem duas se\u00e7\u00f5es.<\/b><\/span><\/span><\/span><\/p>\n

(B)\u00a0<\/b><\/span><\/span><\/span>Ligar e desligar uma l\u00e2mpada, a partir de um interruptor por possuir uma se\u00e7\u00e3o.<\/b><\/span><\/span><\/span><\/p>\n

(C)\u00a0<\/b><\/span><\/span><\/span>Exatamente a mesma fun\u00e7\u00e3o de um interruptor intermedi\u00e1rio.<\/b><\/span><\/span><\/span><\/p>\n

(D)\u00a0<\/b><\/span><\/span><\/span>Exatamente a mesma fun\u00e7\u00e3o de um interruptor simples.<\/b><\/span><\/span><\/span><\/p>\n

(E)\u00a0<\/b><\/span><\/span><\/span>Ligar e desligar uma l\u00e2mpada, a partir de dois interruptores localizados em pontos diferentes.<\/b><\/span><\/span><\/span><\/p>\n

76-Escola Naval 2018\/2019<\/b><\/span><\/span><\/span><\/span><\/span><\/p>\n

<\/p>\n

Analise a figura abaixo.<\/b><\/span><\/span><\/span><\/span><\/p>\n

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

Diferen\u00e7as de potencial de 30 volts j\u00e1 representam, para alguns indiv\u00edduos, risco de fibrila\u00e7\u00e3o induzida (mesmo que o choque el\u00e9trico seja de baixa corrente). Suponha que uma for\u00e7a eletromotriz aplicada entre as m\u00e3os de um ser humano seja, de modo simplificado, equivalente ao circuito mostrado na figura acima, com a magnitude da tens\u00e3o V0\u00a0no capacitor (cora\u00e7\u00e3o) determinando o grau de risco.\u00a0<\/b><\/span><\/span>Se a fem \u00e9 de 30 volts, a pot\u00eancia el\u00e9trica, em watts, dissipada no corpo humano \u00e9 igual a:<\/b><\/span><\/span><\/span><\/span><\/p>\n

(A) 0,9<\/b><\/span><\/span><\/span><\/span><\/p>\n

(B) 0,6<\/b><\/span><\/span><\/span><\/span><\/p>\n

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

(D) 0,3<\/b><\/span><\/span><\/span><\/span><\/p>\n

(E) 0,2<\/b><\/span><\/span><\/span><\/span><\/p>\n

 <\/p>\n

Confira a resolu\u00e7\u00e3o comentada<\/a><\/span><\/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":"

Eletrodin\u00e2mica \u2013 2018\/2019 Corrente el\u00e9trica \u2013 Resist\u00eancia el\u00e9trica, Pot\u00eancia el\u00e9trica e Energia el\u00e9trica 01-(ENEM-MEC-018) 02-(ENEM-MEC-018)   03-(MEDICINA -UNIVERSIDADE MUNICIPAL DE S\u00c3O CAETANO DO SUL \u2013\u2013 USCS-SP \u2013 019) Para carregar a bateria de um smartphone, foi utilizado um carregador que fornece uma diferen\u00e7a de potencial de 5,0 V\u00a0e\u00a0uma corrente el\u00e9trica de intensidade 2,0 A,\u00a0supostamente\u00a0constantes durante todo o processo de carga.<\/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-4848","page","type-page","status-publish","hentry"],"aioseo_notices":[],"_links":{"self":[{"href":"https:\/\/fisicaevestibular.com.br\/novo\/wp-json\/wp\/v2\/pages\/4848","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=4848"}],"version-history":[{"count":4,"href":"https:\/\/fisicaevestibular.com.br\/novo\/wp-json\/wp\/v2\/pages\/4848\/revisions"}],"predecessor-version":[{"id":9912,"href":"https:\/\/fisicaevestibular.com.br\/novo\/wp-json\/wp\/v2\/pages\/4848\/revisions\/9912"}],"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=4848"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}