{"id":3330,"date":"2017-10-01T21:58:18","date_gmt":"2017-10-01T21:58:18","guid":{"rendered":"http:\/\/fisicaevestibular.com.br\/novo\/?page_id=3330"},"modified":"2024-09-04T14:03:30","modified_gmt":"2024-09-04T14:03:30","slug":"resolucao-comentada-eletromagnetismo-2017-2016-2015","status":"publish","type":"page","link":"https:\/\/fisicaevestibular.com.br\/novo\/vestibulares-recentes\/eletricidade\/eletromagnetismo-2017-2016-2015\/resolucao-comentada-eletromagnetismo-2017-2016-2015\/","title":{"rendered":"Resolu\u00e7\u00e3o Comentada ELETROMAGNETISMO \u2013 2017 \u2013 2016 – 2015"},"content":{"rendered":"

Resolu\u00e7\u00e3o Comentada<\/span><\/span><\/span><\/p>\n

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

01- <\/span><\/span><\/span>( ) Na\u00a0<\/b><\/span><\/span>eletriza\u00e7\u00e3o por atrito<\/b><\/span><\/span>, o corpo\u00a0<\/b><\/span><\/span>perde el\u00e9trons\u00a0<\/b><\/span><\/span>passa a\u00a0<\/b><\/span><\/span>ter mais pr\u00f3tons do que possu\u00eda anteriormente<\/b><\/span><\/span>\u00a0e, nesse caso,\u00a0<\/b><\/span><\/span>fica eletrizado com carga positiva<\/b><\/span><\/span>.<\/b><\/span><\/span><\/p>\n

(F)\u00a0<\/b><\/span><\/span>Na\u00a0<\/b><\/span><\/span>eletriza\u00e7\u00e3o por atrito<\/b><\/span><\/span>, o corpo\u00a0<\/b><\/span><\/span>perde el\u00e9trons (cargas negativas), <\/b><\/span><\/span>passa a\u00a0<\/b><\/span><\/span>ter excesso de pr\u00f3tons (cargas positivas),<\/b><\/span><\/span>\u00a0e, nesse caso,\u00a0<\/b><\/span><\/span>fica eletrizado com carga positiva<\/b><\/span><\/span>. Mas,\u00a0<\/b><\/span><\/span>a quantidade de pr\u00f3tons continua a mesma que anteriormente<\/b><\/span><\/span>.<\/b><\/span><\/span><\/p>\n

( )\u00a0<\/b><\/span><\/span>Condutores<\/b><\/span><\/span>\u00a0s\u00e3o corpos que facilitam a\u00a0<\/b><\/span><\/span>passagem da corrente el\u00e9trica, pois\u00a0<\/b><\/span><\/span>possuem grande quantidade de el\u00e9trons livres.<\/b><\/span><\/span><\/p>\n

(V)\u00a0<\/b><\/span><\/span>Condutores<\/b><\/span><\/span>\u00a0\u2013 Os \u00e1tomos dos\u00a0<\/b><\/span><\/span>metais<\/b><\/span><\/span>\u00a0(ferro, ouro, platina, cobre, prata e outros), corpo humano, o solo, o ar \u00famido, etc. t\u00eam\u00a0<\/b><\/span><\/span>seus el\u00e9trons da \u00faltima camada eletr\u00f4nica fracamente unidos<\/b><\/span><\/span>, e podem perd\u00ea-los com facilidade.\u00a0<\/b><\/span><\/span>Esses el\u00e9trons\u00a0<\/b><\/span><\/span>recebem o nome de\u00a0<\/b><\/span><\/span>el\u00e9trons livres.<\/b><\/span><\/span><\/p>\n

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

Devido \u00e0\u00a0<\/b><\/span><\/span>facilidade<\/b><\/span><\/span><\/a>\u00a0de fornecer el\u00e9trons livres,<\/b><\/span><\/span>\u00a0esses corpos s\u00e3o chamados de <\/b><\/span><\/span>condutores el\u00e9tricos\u00a0<\/b><\/span><\/span>e usados para fabricar os fios de cabos e aparelhos el\u00e9tricos, pois s\u00e3o\u00a0<\/b><\/span><\/span>bons condutores do fluxo de el\u00e9trons livres.<\/b><\/span><\/span><\/p>\n

( )\u00a0<\/b><\/span><\/span>Um im\u00e3<\/b><\/span><\/span>, em forma de barra, ao ser\u00a0<\/b><\/span><\/span>cortado ao meio<\/b><\/span><\/span>, d\u00e1 origem a\u00a0<\/b><\/span><\/span>dois novos im\u00e3s<\/b><\/span><\/span>,\u00a0<\/b><\/span><\/span>cada um com apenas um polo (norte ou sul).<\/b><\/span><\/span><\/p>\n

(F)\u00a0<\/b><\/span><\/span>Inseparabilidade dos polos\u00a0<\/b><\/span><\/span>\u2013 Se voc\u00ea\u00a0<\/b><\/span><\/span>quebrar um im\u00e3 e em seguida continuar dividindo os im\u00e3s resultantes<\/b><\/span><\/span>, voc\u00ea observar\u00e1 que\u00a0<\/b><\/span><\/span>cada peda\u00e7o partido continuar\u00e1 sendo um novo im\u00e3 com dois polos<\/b><\/span><\/span>,<\/b><\/span><\/span><\/p>\n

\"\"<\/p>\n

Norte e Sul\u00a0<\/b><\/span><\/span>de maneira que cada peda\u00e7o atraia o outro.\u00a0<\/b><\/span><\/span>N\u00e3o existem polos isolados.<\/b><\/span><\/span><\/p>\n

( ) A\u00a0<\/b><\/span><\/span>b\u00fassola magn\u00e9tica<\/b><\/span><\/span>, cuja extremidade\u00a0<\/b><\/span><\/span>destacada \u00e9 o seu polo norte<\/b><\/span><\/span>, aponta para uma dire\u00e7\u00e3o\u00a0<\/b><\/span><\/span>definida da Terra, pr\u00f3ximo ao polo norte geogr\u00e1fico<\/b><\/span><\/span>.<\/b><\/span><\/span><\/p>\n

(V)<\/b><\/span><\/span>\u00a0A parte\u00a0<\/b><\/span><\/span>destacada da b\u00fassola \u00e9 o seu polo norte e esta aponta para o Polo Sul Magn\u00e9tico<\/b><\/span><\/span>\u00a0da Terra que \u00e9 considerada um\u00a0<\/b><\/span><\/span>grande im\u00e3<\/b><\/span><\/span>. Este ponto localiza-se,\u00a0<\/b><\/span><\/span>de fato, relativamente pr\u00f3ximo ao Polo Norte geogr\u00e1fico da Terra.<\/b><\/span><\/span><\/p>\n

( )\u00a0<\/b><\/span><\/span>Geradores s\u00e3o dispositivos<\/b><\/span><\/span>\u00a0que transformam\u00a0<\/b><\/span><\/span>outras formas de energia em energia el\u00e9trica.<\/b><\/span><\/span><\/p>\n

(V)\u00a0<\/b><\/span><\/span>Exemplos:\u00a0<\/b><\/span><\/span>Baterias e pilhas<\/b><\/span><\/span>\u00a0transformam\u00a0<\/b><\/span><\/span>energia\u00a0<\/b><\/span><\/span>qu\u00edmica em el\u00e9trica<\/b><\/span><\/span>; usinas hidrel\u00e9tricas\u00a0<\/b><\/span><\/span>transformam\u00a0<\/b><\/span><\/span>energia cin\u00e9tica do movimento da \u00e1gua em el\u00e9trica, etc<\/b><\/span><\/span><\/p>\n

( ) O\u00a0<\/b><\/span><\/span>chuveiro el\u00e9trico<\/b><\/span><\/span>\u00a0pode ser considerado um\u00a0<\/b><\/span><\/span>resistor pois transforma energia el\u00e9trica em energia exclusivamente t\u00e9rmica.<\/b><\/span><\/span><\/p>\n

(V)\u00a0<\/b><\/span><\/span>\u00c9 o\u00a0<\/b><\/span><\/span>\u00fanico<\/b><\/span><\/span>\u00a0dispositivo que transforma\u00a0<\/b><\/span><\/span>exclusivamente energia el\u00e9trica em t\u00e9rmica<\/b><\/span><\/span>.<\/b><\/span><\/span><\/p>\n

R- A<\/b><\/span><\/span><\/span><\/p>\n

02- <\/span><\/span><\/span>01. <\/b><\/span><\/span>o\u00a0<\/b><\/span><\/span>vetor campo magn\u00e9tico<\/b><\/span><\/span>\u00a0em cada ponto\u00a0<\/b><\/span><\/span>\u00e9 perpendicular \u00e0 linha de campo magn\u00e9tico<\/b><\/span><\/span>\u00a0que passa por este ponto<\/b><\/span><\/span><\/p>\n

01. Falsa\u00a0\"\"\u00a0<\/b><\/span><\/span>o\u00a0<\/b><\/span><\/span>vetor campo magn\u00e9tico<\/b><\/span><\/span>\u00a0em cada ponto\u00a0<\/b><\/span><\/span>\u00e9\u00a0<\/b><\/span><\/span>tangente\u00a0<\/b><\/span><\/span>\u00e0 linha de campo magn\u00e9tico<\/b><\/span><\/span>\u00a0que passa por este ponto<\/b><\/span><\/span><\/p>\n

02.\u00a0<\/b><\/span><\/span>as <\/b><\/span><\/span>linhas de campo magn\u00e9tico<\/b><\/span><\/span>\u00a0s\u00e3o\u00a0<\/b><\/span><\/span>cont\u00ednuas<\/b><\/span><\/span>, atravessando a barra magn\u00e9tica.<\/b><\/span><\/span><\/p>\n

02. Correta\u00a0\"\"\u00a0<\/b><\/span><\/span>S\u00e3o sempre\u00a0<\/b><\/span><\/span>linhas fechadas e cont\u00ednuas<\/b><\/span><\/span>\u00a0e por isso nunca se cruzam. Fora do \u00edm\u00e3, as linhas\u00a0<\/b><\/span><\/span>saem do polo norte e se dirigem para o polo sul;<\/b><\/span><\/span><\/p>\n

\"\"<\/p>\n

Dentro do \u00edm\u00e3, as linhas s\u00e3o\u00a0<\/b><\/span><\/span>orientadas do polo sul para o polo norte.<\/b><\/span><\/span><\/p>\n

04.\u00a0<\/b><\/span><\/span>as\u00a0<\/b><\/span><\/span>linhas de campo magn\u00e9tico<\/b><\/span><\/span>\u00a0nunca se cruzam.<\/b><\/span><\/span><\/p>\n

04. Correta\u00a0\"\"<\/b><\/span><\/span>\u00a0Veja 02.<\/b><\/span><\/span><\/p>\n

08.\u00a0<\/b><\/span><\/span>por conven\u00e7\u00e3o, as linhas de campo magn\u00e9tico\u00a0<\/b><\/span><\/span>\u201csaem\u201d do polo sul e \u201centram\u201d no polo norte.<\/b><\/span><\/span><\/p>\n

08. Falsa\u00a0\"\"<\/b><\/span><\/span>\u00a0Veja 02.<\/b><\/span><\/span><\/p>\n

16.\u00a0<\/b><\/span><\/span>as regi\u00f5es com\u00a0<\/b><\/span><\/span>menor densidade<\/b><\/span><\/span>\u00a0de linhas de campo magn\u00e9tico pr\u00f3ximas\u00a0<\/b><\/span><\/span>indicam um campo magn\u00e9tico mais intenso.<\/b><\/span><\/span><\/p>\n

16. Falsa\u00a0\"\"\u00a0Perto dos polos<\/b><\/span><\/span>, onde o\u00a0<\/b><\/span><\/span>campo magn\u00e9tico\u00a0\"\"\u00a0tem maior intensidade<\/b><\/span><\/span>, a\u00a0<\/b><\/span><\/span>concentra\u00e7\u00e3o<\/b><\/span><\/span>\u00a0das<\/b><\/span><\/span><\/p>\n

\"\"<\/p>\n

linhas de\u00a0<\/b><\/span><\/span>indu\u00e7\u00e3o \u00e9 maior<\/b><\/span><\/span>, conforme voc\u00ea pode observar na figura.<\/b><\/span><\/span><\/p>\n

32. quebrar um \u00edm\u00e3 em forma de barra<\/b><\/span><\/span>\u00a0\u00e9 uma maneira simples de obter <\/b><\/span><\/span>dois polos magn\u00e9ticos isolados<\/b><\/span><\/span><\/p>\n

32. Falsa\u00a0\"\" Inseparabilidade dos polos<\/b><\/span><\/span>\u00a0\u2013 Se voc\u00ea\u00a0<\/b><\/span><\/span>quebrar\u00a0<\/b><\/span><\/span>um im\u00e3 e em seguida continuar <\/b><\/span><\/span>dividindo<\/b><\/span><\/span><\/p>\n

os im\u00e3s resultantes, voc\u00ea observar\u00e1 que\u00a0<\/b><\/span><\/span>cada peda\u00e7o partido<\/b><\/span><\/span>\u00a0continuar\u00e1 sendo um\u00a0<\/b><\/span><\/span>novo im\u00e3<\/b><\/span><\/span>\u00a0com<\/b><\/span><\/span><\/p>\n

\"\"<\/p>\n

dois p\u00f3los, Norte e Sul<\/b><\/span><\/span>\u00a0de maneira que cada peda\u00e7o atraia o outro.\u00a0<\/b><\/span><\/span>N\u00e3o existem polos isolados.<\/b><\/span><\/span><\/p>\n

64. cargas el\u00e9tricas<\/b><\/span><\/span>\u00a0em repouso\u00a0<\/b><\/span><\/span>n\u00e3o\u00a0<\/b><\/span><\/span>interagem com o campo magn\u00e9tico.<\/b><\/span><\/span><\/p>\n

64. Correta\u00a0\"\"\u00a0<\/b><\/span><\/span>carga\u00a0<\/b><\/span><\/span>em repouso (V=0)\u00a0<\/b><\/span><\/span>ou lan\u00e7ada com velocidade\u00a0\"\"\u00a0paralelamente \u00e0s linhas de<\/b><\/span><\/span><\/p>\n

\"\"<\/p>\n

indu\u00e7\u00e3o de um campo magn\u00e9tico uniforme\u00a0\"\",\u00a0<\/b><\/span><\/span>n\u00e3o est\u00e3o sujeitas a for\u00e7a magn\u00e9tica.<\/b><\/span><\/span>\u00a0\u00a0\u00a0<\/b><\/span><\/span><\/p>\n

R- 70<\/b><\/span><\/span><\/p>\n

03- <\/span><\/span><\/span>Carga el\u00e9trica\u00a0q\u00a0lan\u00e7ada com velocidade\u00a0\"\"\u00a0lan\u00e7ada perpendicularmente \u00e0s linhas de indu\u00e7\u00e3o de um campo magn\u00e9tico uniforme\u00a0\"\"\u00a0\u00a0\u2014\u00a0 observe que, neste caso o \u00e2ngulo entre\u00a0\"\"\u00a0e \"\"\u00a0\u00e9 90<\/b><\/span><\/span>o<\/b><\/span><\/sup><\/span>\u00a0e que sen90<\/b><\/span><\/span>o<\/b><\/span><\/sup><\/span>\u00a0=1.<\/b><\/span><\/span><\/p>\n

Na figura abaixo uma carga positiva\u00a0q\u00a0penetra com velocidade \"\"\u00a0no ponto A numa regi\u00e3o em que existe um campo magn\u00e9tico uniforme\u00a0\"\"\u00a0penetrando na folha. Observe que\u00a0\"\"e\u00a0\"\"\u00a0s\u00e3o perpendiculares e, como a velocidade\u00a0\"\"\u00a0\u00e9 sempre tangente \u00e0 trajet\u00f3ria em cada ponto, a for\u00e7a magn\u00e9tica\u00a0\"\", obtida pela regra da m\u00e3o esquerda e indicada na figura \u00e9 sempre dirigida para o<\/b><\/span><\/span><\/p>\n

\"\"<\/p>\n

\u00a0<\/span>centro de uma circunfer\u00eancia de raio R. Assim, a carga\u00a0q\u00a0realizar\u00e1 um movimento circular uniforme com velocidade de intensidade constante .<\/b><\/span><\/span><\/p>\n

\"\"<\/p>\n

A express\u00e3o matem\u00e1tica dessa for\u00e7a magn\u00e9tica \u00e9 F<\/b><\/span><\/span>m<\/b><\/span><\/sub><\/span> = q.V.B.sen\u03b8 = q.V.B.1\u00a0 \u2014\u00a0\u00a0F<\/b><\/span><\/span>m<\/b><\/span><\/sub><\/span> =q.V.B\u00a0 \u2014\u00a0 lembrando que a for\u00e7a magn\u00e9tica F<\/b><\/span><\/span>m<\/b><\/span><\/sub><\/span>\u00a0\u00e9 respons\u00e1vel pelo movimento circular \u00e9 a for\u00e7a resultante centr\u00edpeta de intensidade F<\/b><\/span><\/span>c <\/b><\/span><\/sub><\/span>= m.V2\/R\u00a0 \u2014\u00a0 F<\/b><\/span><\/span>m<\/b><\/span><\/sub><\/span> = F<\/b><\/span><\/span>c <\/b><\/span><\/sub><\/span> \u2014\u00a0 q.V.B = m.V2\/R\u00a0 \u2014<\/b><\/span><\/span><\/p>\n

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

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

R=m.V\/q.B\u00a0(I)\u00a0\u00a0\u2014\u00a0 o per\u00edodo T (tempo que a carga q demora para efetuar uma volta completa) \u00e9 fornecido por\u00a0 \u2014\u00a0 V=\u0394S\/\u0394t\u00a0 \u2014\u00a0 numa volta completa\u00a0 \u2014\u00a0 \u0394S=2\u03c0R e \u0394t=T\u00a0 \u2014\u00a0 V=2\u03c0R\/T (II)\u00a0 \u2014\u00a0 substituindo II em I\u00a0 \u2014\u00a0 R=m. (2\u03c0R\/T)\/q.B\u00a0 \u2014\u00a0\u00a0T=2\u03c0m\/q.B.\u00a0\u00a0<\/b><\/span><\/span><\/p>\n

Observe que o per\u00edodo (T) do movimento circular n\u00e3o depende da velocidade com que a part\u00edcula q penetra no campo magn\u00e9tico.<\/b><\/span><\/span><\/p>\n

Conforme o enunciado,<\/b><\/span><\/span>\u00a0o el\u00e9tron se movimenta perpendicularmente ao campo magn\u00e9tico, logo, a for\u00e7a magn\u00e9tica \u00e9 a for\u00e7a centr\u00edpeta, sendo assim:<\/b><\/span><\/span><\/p>\n

\"\"<\/p>\n

R- A<\/b><\/span><\/span><\/span><\/p>\n

04- <\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

R- A<\/b><\/span><\/span><\/span><\/p>\n

05- <\/span><\/span><\/span>Na\u00a0<\/b><\/span><\/span>figura abaixo<\/b><\/span><\/span>\u00a0uma carga\u00a0<\/b><\/span><\/span>positiva\u00a0<\/b><\/span><\/span>q<\/b><\/span><\/span>\u00a0penetra com\u00a0<\/b><\/span><\/span>velocidade\"\"<\/b><\/span><\/span>\u00a0no ponto A numa regi\u00e3o em que existe\u00a0<\/b><\/span><\/span>um campo magn\u00e9tico uniforme\u00a0\"\"\u00a0penetrando na folha<\/b><\/span><\/span>. Observe que\"\"\u00a0e\u00a0\"\"\u00a0s\u00e3o\u00a0<\/b><\/span><\/span>perpendiculare<\/b><\/span><\/span>s e, como a velocidade\"\"\u00a0\u00e9 sempre tangente \u00e0 trajet\u00f3ria em cada ponto, a\u00a0<\/b><\/span><\/span>for\u00e7a magn\u00e9tica\u00a0\"\"<\/b><\/span><\/span>, obtida pela regra da m\u00e3o esquerda e indicada na figura \u00e9 sempre dirigida <\/b><\/span><\/span><\/p>\n

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

para o<\/b><\/span><\/span> centro de uma circunfer\u00eancia de raio R<\/b><\/span><\/span>. Assim, a\u00a0<\/b><\/span><\/span>carga\u00a0q\u00a0realizar\u00e1 um movimento circular uniforme com velocidade de intensidade constante .<\/b><\/span><\/span><\/p>\n

\"\"<\/p>\n

A\u00a0<\/b><\/span><\/span>express\u00e3o matem\u00e1tica dessa for\u00e7a magn\u00e9tica \u00e9 Fm=q.V.B.sen\u03b8=q.V.B.1<\/b><\/span><\/span>\u00a0 \u2014\u00a0\u00a0Fm=q.V.B\u00a0 \u2014\u00a0 lembrando que a\u00a0<\/b><\/span><\/span>for\u00e7a magn\u00e9tica Fm,\u00a0<\/b><\/span><\/span>\u00a0respons\u00e1vel pelo movimento circular \u00e9 a\u00a0<\/b><\/span><\/span>for\u00e7a resultante<\/b><\/span><\/span>\u00a0<\/b><\/span><\/span>centr\u00edpeta<\/b><\/span><\/span>\u00a0de intensidade<\/b><\/span><\/span>Fc=m.V2\/R<\/b><\/span><\/span>\u00a0 \u2014\u00a0\u00a0<\/b><\/span><\/span>Fm=Fc<\/b><\/span><\/span>\u00a0 \u2014\u00a0 q.V.B=m.V2\/R\u00a0 \u2014\u00a0<\/b><\/span><\/span>R=m.V\/q.B\u00a0(express\u00e3o matem\u00e1tica pedida).\u00a0\u00a0<\/b><\/span><\/span><\/span><\/p>\n

 <\/p>\n

06- <\/span><\/span><\/span>As\u00a0<\/b><\/span><\/span>nanopart\u00edculas magn\u00e9ticas\u00a0<\/b><\/span><\/span>s\u00e3o sistemas formados por\u00a0<\/b><\/span><\/span>min\u00fasculos im\u00e3s microsc\u00f3picos\u00a0<\/b><\/span><\/span>da\u00a0<\/b><\/span><\/span>ordem denam\u00f4metros (10<\/b><\/span><\/span>-9<\/b><\/span><\/sup><\/span>\u00a0m).<\/b><\/span><\/span><\/span><\/span><\/p>\n

Na\u00a0<\/b><\/span><\/span>magnetohipertermia\u00a0<\/b><\/span><\/span>elas s\u00e3o\u00a0<\/b><\/span><\/span>injetadas somente sobre o tumor\u00a0<\/b><\/span><\/span>sendo <\/b><\/span><\/span>fagocitadas<\/b><\/span><\/span>\u00a0(englobadas) pelas\u00a0<\/b><\/span><\/span>c\u00e9lulas tumorais\u00a0<\/b><\/span><\/span>e submetidas a um <\/b><\/span><\/span>campo magn\u00e9tico vari\u00e1vel (<\/b><\/span><\/span>de\u00a0<\/b><\/span><\/span>frequ\u00eancia de oscila\u00e7\u00e3o<\/b><\/span><\/span><\/span><\/span><\/p>\n

aproximada de 10<\/b><\/span><\/span>5<\/b><\/span><\/sup><\/span> Hz).<\/b><\/span><\/span><\/span><\/span><\/p>\n

Esse\u00a0<\/b><\/span><\/span>campo magn\u00e9tico alternado\u00a0<\/b><\/span><\/span>faz com que as\u00a0<\/b><\/span><\/span>nanopart\u00edculas girem, <\/b><\/span><\/span>aproximadamente\u00a0<\/b><\/span><\/span>10<\/b><\/span><\/span>5<\/b><\/span><\/sup><\/span>\u00a0vezes por segundo,\u00a0<\/b><\/span><\/span>se\u00a0<\/b><\/span><\/span>orientando sempre no sentido do campo magn\u00e9tico vari\u00e1vel \"\".<\/b><\/span><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Nesse\u00a0<\/b><\/span><\/span>movimento de rota\u00e7\u00e3o\u00a0<\/b><\/span><\/span>as\u00a0<\/b><\/span><\/span>nanopart\u00edculas no interior do tumor, chocam\u00a0<\/b><\/span><\/span>com as\u00a0<\/b><\/span><\/span>c\u00e9lulas tumorais<\/b><\/span><\/span>\u00a0e,\u00a0<\/b><\/span><\/span>devido ao atrito\u00a0<\/b><\/span><\/span>com as mesmas, <\/b><\/span><\/span>provocam um aumento de energia sob forma de calor.<\/b><\/span><\/span><\/span><\/span><\/p>\n

R- B<\/b><\/span><\/span><\/span><\/span><\/span><\/p>\n

07- <\/span><\/span><\/span>A\u00a0<\/b><\/span><\/span>dire\u00e7\u00e3o e sentido de\u00a0\"\"\u00a0\u00a0<\/b><\/span><\/span>\u00e9 fornecida pela\u00a0<\/b><\/span><\/span>regra da m\u00e3o esquerda <\/b><\/span><\/span>(veja figura) onde o\u00a0<\/b><\/span><\/span>dedo<\/b><\/span><\/span><\/p>\n

\"\"<\/p>\n

m\u00e9dio<\/b><\/span><\/span>\u00a0indica o\u00a0<\/b><\/span><\/span>sentido da corrente el\u00e9trica i,<\/b><\/span><\/span>\u00a0o\u00a0<\/b><\/span><\/span>polegar<\/b><\/span><\/span>\u00a0a\u00a0<\/b><\/span><\/span>for\u00e7a magn\u00e9tica<\/b><\/span><\/span>\u00a0\"\"\u00a0e o i<\/b><\/span><\/span>ndicador<\/b><\/span><\/span>\u00a0o\u00a0<\/b><\/span><\/span>campo magn\u00e9tico\u00a0\"\".<\/b><\/span><\/span><\/p>\n

Adapte sua m\u00e3o esquerda na alternativa\u00a0<\/b><\/span><\/span>(a)<\/b><\/span><\/span>\u00a0com o\u00a0<\/b><\/span><\/span>indicador\u00a0<\/b><\/span><\/span>(\"\") entrando na folha, o\u00a0<\/b><\/span><\/span>m\u00e9dio<\/b><\/span><\/span>\u00a0(i) para baixo e verificar\u00e1 que o\u00a0<\/b><\/span><\/span>polegar<\/b><\/span><\/span>\u00a0(\"\") estar\u00e1 orientado para a direita.<\/b><\/span><\/span><\/p>\n

R- A<\/b><\/span><\/span><\/span><\/p>\n

08- <\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

\"\"<\/p>\n

Vamos considerar, na figura, que na\u00a0<\/b><\/span><\/span>situa\u00e7\u00e3o inicial a parte do fio semirraspada esteja em contato com o mancal fazendo com que circule corrente pela espira.<\/b><\/span><\/span><\/span><\/span><\/p>\n

Considerando tamb\u00e9m que o\u00a0<\/b><\/span><\/span>polo A da pilha seja negativo e o\u00a0B\u00a0positivo, <\/b><\/span><\/span>a\u00a0<\/b><\/span><\/span>corrente el\u00e9trica\u00a0<\/b><\/span><\/span>fornecida pela\u00a0<\/b><\/span><\/span>pilha ir\u00e1 circular no sentido indicado na figura<\/b><\/span><\/span>, pois a\u00a0<\/b><\/span><\/span>corrente i sai do polo positivo e se dirige ao polo negativo.<\/b><\/span><\/span><\/span><\/span><\/p>\n

Colocando<\/b><\/span><\/span>\u00a0o\u00a0<\/b><\/span><\/span>polo Norte na face superior do im\u00e3 o campo magn\u00e9tico\u00a0\"\"tem dire\u00e7\u00e3o vertical e sentido para cima.<\/b><\/span><\/span><\/span><\/span><\/p>\n

\"\"Utilizando a\u00a0<\/b><\/span><\/span>regra da m\u00e3o esquerda nos ramos superior e inferior (figuras acima)\u00a0<\/b><\/span><\/span>voc\u00ea verifica que as for\u00e7as que agem sobre eles fazem a espira girar no sentido hor\u00e1rio.<\/b><\/span><\/span><\/span><\/span><\/p>\n

R- E<\/b><\/span><\/span><\/span><\/span><\/span><\/p>\n

Observa\u00e7\u00f5es:<\/b><\/span><\/span><\/span><\/span><\/p>\n

\"\"\u00a0<\/span>Nos\u00a0<\/b><\/span><\/span>dois ramos paralelos \u00e0\u00a0\"\"\u00a0as for\u00e7as s\u00e3o nulas,\u00a0<\/b><\/span><\/span>pois\u00a0<\/b><\/span><\/span>F = Bilsen(0<\/b><\/span><\/span>o<\/b><\/span><\/sup><\/span> ou 180<\/b><\/span><\/span>o<\/b><\/span><\/sup><\/span>) = Bil.0\u00a0<\/b><\/span><\/span>= 0.<\/b><\/span><\/span><\/span><\/span><\/p>\n

\"\"\u00a0<\/span>A\u00a0<\/b><\/span><\/span>extremidade semirraspada impede<\/b><\/span><\/span>\u00a0que, a\u00a0<\/b><\/span><\/span>corrente,<\/b><\/span><\/span>\u00a0ap\u00f3s\u00a0<\/b><\/span><\/span>meia volta se inverta, invertend<\/b><\/span><\/span>o as\u00a0<\/b><\/span><\/span>for\u00e7as que podem impedir o giro no sentido hor\u00e1rio.<\/b><\/span><\/span><\/p>\n

09- <\/span><\/span><\/span>For\u00e7a magn\u00e9tica sobre um fio retil\u00edneo percorrido por corrente el\u00e9trica i<\/b><\/span><\/span><\/p>\n

\"\"<\/p>\n

F<\/b><\/span><\/span>m<\/b><\/span><\/sub><\/span>\u00a0<\/b><\/span><\/span>\u2013\u00a0<\/b><\/span><\/span>intensidade da for\u00e7a magn\u00e9tica<\/b><\/span><\/span>\u00a0<\/b><\/span><\/span>que age sobre o fio \u2013 medida em newton (N), no SI.<\/b><\/span><\/span><\/p>\n

B<\/b><\/span><\/span>\u00a0\u2013\u00a0<\/b><\/span><\/span>intensidade do campo magn\u00e9tico<\/b><\/span><\/span>\u00a0\u2013\u00a0<\/b><\/span><\/span>medido em tesla (T), no SI.<\/b><\/span><\/span><\/p>\n

i<\/b><\/span><\/span>\u00a0\u2013\u00a0<\/b><\/span><\/span>corrente el\u00e9trica no fio<\/b><\/span><\/span>\u00a0\u2013\u00a0<\/b><\/span><\/span>medida em amp\u00e8re (A), no SI.<\/b><\/span><\/span><\/p>\n

\u03b8\u00a0<\/b><\/span><\/span>\u2013\u00a0<\/b><\/span><\/span>\u00e2ngulo entre a dire\u00e7\u00e3o de B e de i.<\/b><\/span><\/span><\/p>\n

\"\"<\/p>\n

\"\"<\/p>\n

A\u00a0<\/b><\/span><\/span>for\u00e7a magn\u00e9tica nos fios<\/b><\/span><\/span>\u00a0<\/b><\/span><\/span>n\u00e3o provoca<\/b><\/span><\/span>\u00a0<\/b><\/span><\/span>torque resultante<\/b><\/span><\/span>,\u00a0<\/b><\/span><\/span>ou seja, a <\/b><\/span><\/span>espira n\u00e3o consegue girar,<\/b><\/span><\/span>\u00a0<\/b><\/span><\/span>pois o\u00a0<\/b><\/span><\/span>suporte S impede esse giro<\/b><\/span><\/span>\u00a0que seria no sentido anti-hor\u00e1rio.<\/b><\/span><\/span><\/p>\n

Assim,\u00a0a espira<\/b><\/span><\/span>\u00a0<\/b><\/span><\/span>permanecer\u00e1\u00a0<\/b><\/span><\/span>na sua posi\u00e7\u00e3o original de equil\u00edbrio.<\/b><\/span><\/span><\/p>\n

R- B<\/b><\/span><\/span><\/span><\/p>\n

10- <\/span><\/span><\/span>For\u00e7a Magn\u00e9tica sobre um condutor retil\u00edneo imerso num campo magn\u00e9tico uniforme<\/b><\/span><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

\"\"<\/p>\n

\"\"<\/p>\n

R- A<\/b><\/span><\/span><\/span><\/p>\n

11- <\/span><\/span><\/span><\/span><\/span><\/p>\n

Campo magn\u00e9tico originado por um condutor retil\u00edneo extenso percorrido por corrente\u00a0el\u00e9trica<\/b><\/span><\/span><\/span><\/span><\/p>\n

Dire\u00e7\u00e3o e sentido do campo magn\u00e9tico \"\"<\/b><\/span><\/span><\/p>\n

\u00a0<\/span>Um dos<\/b><\/span><\/span>\u00a0<\/b><\/span><\/span>processos pr\u00e1tico<\/b><\/span><\/span>s<\/b><\/span><\/span>\u00a0<\/b><\/span><\/span>para se determinar a\u00a0<\/b><\/span><\/span>dire\u00e7\u00e3o e o sentido do vetor indu\u00e7\u00e3o<\/b><\/span><\/span>\u00a0<\/b><\/span><\/span>magn\u00e9tica\u00a0\"\"\u00a0\u00a0ou vetor campo magn\u00e9tico\u00a0\"\", \u00e9 a regra da m\u00e3o direita.<\/b><\/span><\/span>\u00a0Esse\u00a0<\/b><\/span><\/span>sentido de\u00a0\"\"\u00a0depende do sentido da corrente que o origina.<\/b><\/span><\/span><\/p>\n

Voc\u00ea\u00a0<\/b><\/span><\/span>coloca o polegar no sentido da corrente com a m\u00e3o espalmada (primeira figura),\u00a0<\/b><\/span><\/span>em seguida<\/b><\/span><\/span><\/p>\n

\"\"<\/p>\n

voc\u00ea\u00a0<\/b><\/span><\/span>fecha a m\u00e3o para pegar o\u00a0fio (segunda figura)\u00a0<\/b><\/span><\/span>e o\u00a0<\/b><\/span><\/span>sentido da \u201cfechada\u201d de m\u00e3o \u00e9 o sentido do vetor\u00a0\"\"\u00a0(terceira figura).<\/b><\/span><\/span><\/p>\n

Observe na\u00a0<\/b><\/span><\/span>terceira figura que \u00a0\"\"\u00a0\u00e9 sempre tangente \u00e0s linhas de indu\u00e7\u00e3o em cada ponto.<\/b><\/span><\/span><\/p>\n

Intensidade do campo magn\u00e9tico\u00a0\"\"<\/b><\/span><\/span><\/p>\n

\"\"<\/p>\n

\u00a0<\/span>No caso do\u00a0<\/b><\/span><\/span>exerc\u00edcio,<\/b><\/span><\/span>\u00a0no\u00a0<\/b><\/span><\/span>centro do quadrado, a intensidade (m\u00f3dulo) do campo magn\u00e9tico<\/b><\/span><\/span>\u00a0originado por\u00a0<\/b><\/span><\/span>qualquer fio \u00e9 o mesmo,<\/b><\/span><\/span>\u00a0pois na <\/b><\/span><\/span>express\u00e3o B = \u03bc.i\/2.\u03c0.r todos os elementos s\u00e3o constantes.<\/b><\/span><\/span><\/p>\n

Assim o que\u00a0<\/b><\/span><\/span>muda no centro de cada quadrado<\/b><\/span><\/span>\u00a0\u00e9 a\u00a0<\/b><\/span><\/span>dire\u00e7\u00e3o e sentido de\u00a0\"\"fornecidos pela regra da m\u00e3o direita (veja teoria acima).<\/b><\/span><\/span><\/p>\n

Analise atentamente as figuras abaixo\u00a0<\/b><\/span><\/span>que fornecem o<\/b><\/span><\/span>\u00a0campo magn\u00e9tico resultante (total) no centro de cada quadrado.<\/b><\/span><\/span><\/p>\n

\"\"<\/p>\n

R- D<\/b><\/span><\/span><\/span><\/p>\n

12- <\/span><\/span><\/span><\/span><\/span><\/p>\n

Dire\u00e7\u00e3o e sentido do campo magn\u00e9tico\u00a0\"\"\u00a0originado por um fio retil\u00edneo percorrido por corrente el\u00e9trica i<\/b><\/span><\/span><\/span><\/span><\/p>\n

\u00a0<\/span>Um dos<\/b><\/span><\/span>\u00a0<\/b><\/span>processos pr\u00e1ticos\u00a0<\/b><\/span>para se determinar a\u00a0<\/b><\/span>dire\u00e7\u00e3o e o sentido do vetor indu\u00e7\u00e3o magn\u00e9tica\u00a0\"\"\u00a0ou vetor campo magn\u00e9tico\u00a0\"\", \u00e9 a regra da m\u00e3o direita<\/b><\/span>. Esse\u00a0<\/b><\/span>sentido de\u00a0\"\"\u00a0depende do sentido da corrente que o origina.<\/b><\/span><\/span><\/span><\/p>\n

Voc\u00ea\u00a0<\/b><\/span><\/span>coloca o polegar no sentido da corrente com a m\u00e3o espalmada (primeira figura),\u00a0<\/b><\/span><\/span>em seguida<\/b><\/span><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

voc\u00ea\u00a0<\/b><\/span><\/span>fecha a m\u00e3o para pegar o\u00a0fio (segunda figura)\u00a0<\/b><\/span><\/span>e o\u00a0<\/b><\/span><\/span>sentido da \u201cfechada\u201d de m\u00e3o \u00e9 o sentido do vetor\u00a0\"\"\u00a0(terceira figura).<\/b><\/span><\/span><\/span><\/span><\/p>\n

Observe na\u00a0<\/b><\/span><\/span>terceira figura que \u00a0\"\"\u00a0\u00e9 sempre tangente \u00e0s linhas de indu\u00e7\u00e3o em cada ponto.<\/b><\/span><\/span><\/span><\/span><\/p>\n

Intensidade do campo magn\u00e9tico\u00a0\"\"<\/b><\/span><\/span><\/span><\/span><\/p>\n

Comprova-se\u00a0<\/b><\/span><\/span>experimentalmente que a intensidade do campo magn\u00e9tico\u00a0\"\"\u00a0<\/b><\/span><\/span>depende da\u00a0<\/b><\/span><\/span>intensidade da corrente el\u00e9trica i,\u00a0<\/b><\/span><\/span>da\u00a0<\/b><\/span><\/span>dist\u00e2ncia r do fio at\u00e9 o ponto (P) onde se quer o campo magn\u00e9tico e do meio onde o condutor se encontra.\u00a0<\/b><\/span><\/span>Essa\u00a0<\/b><\/span><\/span>depend\u00eancia de\u00a0\"\"\u00a0com o meio\u00a0<\/b><\/span><\/span>\u00e9 fornecida pela\u00a0<\/b><\/span><\/span>constante \u03bc que recebe o nome de permeabilidade magn\u00e9tica do meio e no v\u00e1cuo ela vale \u03bc<\/b><\/span><\/span>\u00a0<\/b><\/span><\/span>= 4\u03c0.10<\/b><\/span><\/span>-7<\/b><\/span><\/span>\u00a0T.m\/A. Matematicamente:<\/b><\/span><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

\"\"<\/p>\n

Agora vamos calcular o campo el\u00e9trico no interior da espira circular:<\/b><\/span><\/span><\/span><\/span><\/p>\n

Dire\u00e7\u00e3o e sentido do vetor campo magn\u00e9tico\"\"\u00a0no interior de uma espira circular<\/b><\/span><\/span><\/span><\/span><\/p>\n

Na\u00a0<\/b><\/span><\/span>figura da esquerda\u00a0<\/b><\/span><\/span>voc\u00ea observa um\u00a0<\/b><\/span><\/span>condutor sob forma de espira circular com centro O e raio R\u00a0<\/b><\/span><\/span>sendo\u00a0<\/b><\/span><\/span>percorrido por uma corrente el\u00e9trica de intensidade i<\/b><\/span><\/span>.<\/b><\/span><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Em\u00a0<\/b><\/span><\/span>torno da espira (figura da direita)\u00a0<\/b><\/span><\/span>surge um\u00a0<\/b><\/span><\/span>campo magn\u00e9tico\u00a0<\/b><\/span><\/span>cuja<\/b><\/span><\/span>dire\u00e7\u00e3o e sentido\u00a0<\/b><\/span><\/span>\u00e9 fornecido pela\u00a0<\/b><\/span><\/span>regra da m\u00e3o direita\u00a0<\/b><\/span><\/span>(voc\u00ea coloca o polegar no sentido da corrente com a m\u00e3o espalmada, em seguida voc\u00ea fecha a m\u00e3o como se fosse pegar o pegar o fio e o sentido da \u201cfechada\u201d de m\u00e3o \u00e9 o sentido do vetor\u00a0\"\"),\u00a0<\/b><\/span><\/span>considerando cada pequeno trecho da circunfer\u00eancia como sendo um condutor retil\u00edneo.<\/b><\/span><\/span><\/span><\/span><\/p>\n

Observe na figura da direita que no\u00a0<\/b><\/span><\/span>plano do c\u00edrculo,\u00a0<\/b><\/span><\/span>todas as\u00a0<\/b><\/span><\/span>linhas de for\u00e7a t\u00eam sentidos coincidentes e que no centro da espira, em qualquer posi\u00e7\u00e3o que voc\u00ea use a regra da m\u00e3o direita<\/b><\/span><\/span>, o\u00a0<\/b><\/span><\/span>campo magn\u00e9tico\u00a0\"\"\u00a0\u00e9 perpendicular ao plano do papel e, nesse exemplo, entrando nele.<\/b><\/span><\/span><\/span><\/span><\/p>\n

Intensidade de\u00a0\"\"<\/b><\/span><\/span><\/span><\/span><\/p>\n

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

\"\"<\/p>\n

\"\"<\/p>\n

R- E<\/b><\/span><\/span><\/span><\/span><\/span><\/p>\n

13- <\/span><\/span><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

No\u00a0<\/b><\/span><\/span>interior do solenoide\u00a0<\/b><\/span><\/span>o\u00a0<\/b><\/span><\/span>campo magn\u00e9tico \u00e9 praticamente uniforme\u00a0<\/b><\/span><\/span>e\u00a0<\/b><\/span><\/span>sua intensidade \u00e9 constante e vale:<\/b><\/span><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

\u00a0<\/span>A\u00a0<\/b><\/span><\/span>express\u00e3o acima \u00e9 v\u00e1lida para solenoides sem n\u00facleo e,<\/b><\/span><\/span>\u00a0se voc\u00ea colocar no\u00a0<\/b><\/span><\/span>interior\u00a0<\/b><\/span><\/span>do\u00a0<\/b><\/span><\/span>solenoide<\/b><\/span><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

um\u00a0<\/b><\/span><\/span>n\u00facleo de material ferromagn\u00e9tico,\u00a0<\/b><\/span><\/span>a\u00a0<\/b><\/span><\/span>intensidade do campo magn\u00e9tico\u00a0<\/b><\/span><\/span>gerado fica\u00a0<\/b><\/span><\/span>muito aumentada ele ser\u00e1 um eletro\u00edm\u00e3 (im\u00e3 muito possante). \u00a0<\/b><\/span><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

R \u2013 B<\/b><\/span><\/span><\/span><\/span><\/span><\/p>\n

14- <\/span><\/span><\/span>A intensidade do campo magn\u00e9tico\u00a0<\/b><\/span><\/span>originado por uma\u00a0<\/b><\/span><\/span>bobina chata<\/b><\/span><\/span>\u00a0\u00e9 fornecido por:<\/b><\/span><\/span><\/p>\n

\"\"<\/p>\n

Observe que\u00a0<\/b><\/span><\/span>o enunciado afirma\u00a0<\/b><\/span><\/span>que as\u00a0<\/b><\/span><\/span>duas bobinas <\/b><\/span><\/span>s\u00e3o percorridas\u00a0<\/b><\/span><\/span>pela mesma intensidade de corrente el\u00e9trica e mesma permeabilidade magn\u00e9tica do meio.<\/b><\/span><\/span><\/p>\n

\"\"<\/p>\n

15- <\/span><\/span><\/span><\/p>\n

Dire\u00e7\u00e3o e sentido do campo magn\u00e9tico\u00a0\"\"\u00a0em fios retil\u00edneos<\/b><\/span><\/span><\/p>\n

\u00a0<\/span>Um dos<\/b><\/span><\/span>\u00a0<\/b><\/span><\/span>processos pr\u00e1ticos\u00a0<\/b><\/span><\/span>para se determinar a\u00a0<\/b><\/span><\/span>dire\u00e7\u00e3o e o sentido do vetor indu\u00e7\u00e3o magn\u00e9tica\u00a0B\u00a0ou vetor campo magn\u00e9tico\u00a0\"\", \u00e9 a regra da m\u00e3o direita<\/b><\/span><\/span>. Esse\u00a0<\/b><\/span><\/span>sentido de\u00a0\"\"\u00a0depende do sentido da corrente que o origina.<\/b><\/span><\/span><\/p>\n

Voc\u00ea\u00a0<\/b><\/span><\/span>coloca o polegar no sentido da corrente com a m\u00e3o espalmada (primeira figura),\u00a0<\/b><\/span><\/span>em seguida<\/b><\/span><\/span><\/p>\n

\"\"<\/p>\n

voc\u00ea\u00a0<\/b><\/span><\/span>fecha a m\u00e3o para pegar o\u00a0fio (segunda figura)\u00a0<\/b><\/span><\/span>e o\u00a0<\/b><\/span><\/span>sentido da \u201cfechada\u201d de m\u00e3o \u00e9 o sentido do vetor\u00a0\"\"\u00a0(terceira figura).<\/b><\/span><\/span><\/p>\n

Observe na\u00a0<\/b><\/span><\/span>terceira figura que \u00a0\"\"\u00a0\u00e9 sempre tangente \u00e0s linhas de indu\u00e7\u00e3o em cada ponto.<\/b><\/span><\/span><\/p>\n

Intensidade do campo magn\u00e9tico\u00a0\"\"<\/b><\/span><\/span><\/p>\n

Comprova-se\u00a0<\/b><\/span><\/span>experimentalmente que a intensidade do campo magn\u00e9tico\u00a0\"\"\u00a0<\/b><\/span><\/span>depende da<\/b><\/span><\/span>intensidade da corrente el\u00e9trica i,\u00a0<\/b><\/span><\/span>da\u00a0<\/b><\/span><\/span>dist\u00e2ncia r do fio at\u00e9 o ponto (P) onde se quer o campo magn\u00e9tico e do meio onde o condutor se encontra.\u00a0<\/b><\/span><\/span>Essa\u00a0<\/b><\/span><\/span>depend\u00eancia de\u00a0\"\"\u00a0com o meio\u00a0<\/b><\/span><\/span>\u00e9 fornecida pela\u00a0<\/b><\/span><\/span>constante \u03bc que recebe o nome de permeabilidade magn\u00e9tica do meio e no v\u00e1cuo ela vale \u03bc<\/b><\/span><\/span>\u00a0<\/b><\/span><\/span>= 4\u03c0.10-7\u00a0T.m\/A. Matematicamente:<\/b><\/span><\/span><\/p>\n

\"\"<\/p>\n

\"\"<\/p>\n

\"\"<\/p>\n

Dire\u00e7\u00e3o e sentido do campo magn\u00e9tico originado no interior de uma espira<\/b><\/span><\/span><\/p>\n

\"\"<\/p>\n

\"\"<\/p>\n

\"\"<\/p>\n

\"\"<\/p>\n

\"\"<\/p>\n

R- D<\/b><\/span><\/span><\/span><\/p>\n

16- <\/span><\/span><\/span>As figuras abaixo representam a posi\u00e7\u00e3o da espira num giro anti-hor\u00e1rio de 0o\u00a0a 90o\u00a0da espira:<\/b><\/span><\/span><\/span><\/span><\/p>\n

\"\"Aplicando a\u00a0<\/b><\/span><\/span>regra da m\u00e3o direita\u00a0<\/b><\/span><\/span>na\u00a0<\/b><\/span><\/span>situa\u00e7\u00e3o inicial<\/b><\/span><\/span>\u00a0(figura I)\u00a0<\/b><\/span><\/span>\u201cpolegar no sentido da corrente\u00a0<\/b><\/span><\/span>e a<\/b><\/span><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

\u2018<\/span>fechada\u2019 da m\u00e3o por dentro da espira no sentido de B\u201d<\/b><\/span><\/span>\u00a0voc\u00ea verifica que o<\/b><\/span><\/span>sentido inicial de i \u00e9 ABCD.<\/b><\/span><\/span><\/span><\/span><\/p>\n

\u00c0 medida que a espira gira<\/b><\/span><\/span>\u00a0no sentido anti-hor\u00e1rio a\u00a0<\/b><\/span><\/span>intensidade do fluxo magn\u00e9tico\u00a0<\/b><\/span><\/span>no interior da espira e consequentemente da\u00a0<\/b><\/span><\/span>corrente el\u00e9trica i vai diminuindo\u00a0<\/b><\/span><\/span>(mas mantendo o sentido ABCD)\u00a0<\/b><\/span><\/span>at\u00e9 completar o giro de 90<\/b><\/span><\/span>o<\/b><\/span><\/sup><\/span>\u00a0<\/b><\/span>(figura II)\u00a0<\/b><\/span><\/span>quando se anulam.<\/b><\/span><\/span><\/span><\/span><\/p>\n

R- C<\/b><\/span><\/span><\/span><\/span><\/span><\/p>\n

17- <\/span><\/span><\/span>Quando um\u00a0<\/b><\/span><\/span>solenoide \u00e9 percorrido por corrente el\u00e9trica<\/b><\/span><\/span>, a configura\u00e7\u00e3o de suas linhas de indu\u00e7\u00e3o \u00e9 obtida pela reuni\u00e3o das configura\u00e7\u00f5es\u00a0<\/b><\/span><\/span>de cada espira o que equivale \u00e0 configura\u00e7\u00e3o das linhas de indu\u00e7\u00e3o de um im\u00e3 natural.<\/b><\/span><\/span><\/p>\n

O\u00a0<\/b><\/span><\/span>sentido das linhas de indu\u00e7\u00e3o no solenoide \u00e9 fornecido pela regra da m\u00e3o direita aplicada em uma<\/b><\/span><\/span><\/p>\n

\"\"<\/p>\n

de suas espiras (figura 2) e<\/b><\/span><\/span>\u00a0<\/b><\/span><\/span>em seu interior o campo magn\u00e9tico \u00e9 praticamente uniforme<\/b><\/span><\/span>\u00a0<\/b><\/span><\/span>(figura 1<\/b><\/span><\/span>) e fora s\u00e3o linhas que saem do polo norte e chegam ao polo sul.<\/b><\/span><\/span><\/p>\n

Observe que em todos os infinitos\u00a0<\/b><\/span><\/span>pontos onde est\u00e1 a espira o campo magn\u00e9tico\u00a0\"\"\u00a0tem dire\u00e7\u00e3o<\/b><\/span><\/span>\u00a0<\/b><\/span><\/span>horizontal e sentido para a direita<\/b><\/span><\/span>\u00a0(poderia ser para a esquerda).<\/b><\/span><\/span><\/p>\n

\"\"<\/p>\n

Na\u00a0<\/b><\/span><\/span>espira da figura da direita acima<\/b><\/span><\/span>, voc\u00ea pode aplicar a\u00a0<\/b><\/span><\/span>regra da m\u00e3o esquerda para cada trecho do fio:<\/b><\/span><\/span><\/p>\n

Regra da m\u00e3o esquerda<\/b><\/span><\/span>: O dedo\u00a0<\/b><\/span><\/span>m\u00e9dio indica o sentido da corrente el\u00e9trica i,<\/b><\/span><\/span>\u00a0<\/b><\/span><\/span>o indicador mostra<\/b><\/span><\/span><\/p>\n

\"\"<\/p>\n

o sentido do campo magn\u00e9tico\u00a0\"\"\u00a0<\/b><\/span><\/span>e\u00a0<\/b><\/span><\/span>o polegar a for\u00e7a magn\u00e9tica\u00a0\"\".<\/b><\/span><\/span><\/p>\n

Intensidade da for\u00e7a magn\u00e9tica:<\/b><\/span><\/span><\/p>\n

\"\"<\/p>\n

F<\/b><\/span><\/span>m<\/b><\/span><\/sub><\/span>\u00a0<\/b><\/span><\/span>\u2013 intensidade da for\u00e7a magn\u00e9tica que age sobre o fio \u2013\u00a0<\/b><\/span><\/span>medida em newton (N), no SI.<\/b><\/span><\/span><\/p>\n

B\u00a0<\/b><\/span><\/span>\u2013 intensidade do campo magn\u00e9tico \u2013\u00a0<\/b><\/span><\/span>medido em tesla (T), no SI<\/b><\/span><\/span>.<\/b><\/span><\/span><\/p>\n

i\u00a0<\/b><\/span><\/span>\u2013 corrente el\u00e9trica no fio \u2013\u00a0<\/b><\/span><\/span>medida em amp\u00e8re (A), no SI.<\/b><\/span><\/span><\/p>\n

\u03b8\u00a0<\/b><\/span><\/span>\u2013\u00a0<\/b><\/span><\/span>\u00e2ngulo entre a dire\u00e7\u00e3o de B e de i<\/b><\/span><\/span>.<\/b><\/span><\/span><\/p>\n

\"\"<\/p>\n

\"\"<\/p>\n

18- <\/b><\/span><\/span><\/span>Quando um\u00a0<\/b><\/span><\/span>solenoide \u00e9 percorrido por corrente el\u00e9trica<\/b><\/span><\/span>, a configura\u00e7\u00e3o de suas linhas de indu\u00e7\u00e3o \u00e9 obtida pela reuni\u00e3o das <\/b><\/span><\/span>configura\u00e7\u00f5es de cada espira<\/b><\/span><\/span>\u00a0o que equivale \u00e0\u00a0<\/b><\/span><\/span>configura\u00e7\u00e3o das linhas de indu\u00e7\u00e3o de um im\u00e3 natural.<\/b><\/span><\/span><\/p>\n

O\u00a0<\/b><\/span><\/span>sentido<\/b><\/span><\/span>\u00a0das linhas de indu\u00e7\u00e3o no solenoide \u00e9 fornecido pela\u00a0<\/b><\/span><\/span>regra da m\u00e3o direita<\/b><\/span><\/span>\u00a0aplicada em uma<\/b><\/span><\/span><\/p>\n

\"\"<\/p>\n

de suas espiras\u00a0<\/b><\/span><\/span>(figura 2)<\/b><\/span><\/span>\u00a0e em seu interior o campo magn\u00e9tico \u00e9 praticamente uniforme\u00a0<\/b><\/span><\/span>(figura 1) e fora s\u00e3o linhas que saem do polo norte e chegam ao polo sul.<\/b><\/span><\/span><\/p>\n

\"\"\u00a0<\/span>As linhas\u00a0<\/b><\/span><\/span>de for\u00e7a do campo magn\u00e9tico produzido por um solenoide s\u00e3o id\u00eanticas aos do campo magn\u00e9tico produzido por um im\u00e3.<\/b><\/span><\/span><\/p>\n

\"\"<\/p>\n

Na pr\u00e1tica, \u00e9\u00a0<\/b><\/span><\/span>indiferente<\/b><\/span><\/span>\u00a0produzir-se um campo magn\u00e9tico por um \u00edm\u00e3 ou por um solenoide.<\/b><\/span><\/span><\/p>\n

Observe\u00a0<\/b><\/span><\/span>nas figuras abaixo<\/b><\/span><\/span>\u00a0que, como a corrente el\u00e9trica sai do\u00a0<\/b><\/span><\/span>polo positivo da bateria<\/b><\/span><\/span>, utilizando<\/b><\/span><\/span><\/p>\n

\"\"<\/p>\n

a regra da\u00a0<\/b><\/span><\/span>m\u00e3o direita, os polos do im\u00e3 ter\u00e3o a distribui\u00e7\u00e3o da figura da direita.<\/b><\/span><\/span><\/p>\n

R- C<\/b><\/span><\/span><\/span><\/p>\n

19-<\/b><\/span><\/span><\/span> I.\u00a0<\/b><\/span><\/span>Correta\u00a0<\/b><\/span><\/span>\uf0de<\/b><\/span><\/span><\/span>\u00a0Lei de Faraday-Lenz.<\/b><\/span><\/span>\u00a0<\/b><\/span><\/span>For\u00e7a eletromotriz gerada por um condutor m\u00f3vel num campo el\u00e9trico uniforme\u00a0\u00a0\u2014\u00a0\u00a0<\/b><\/span><\/span>esse condutor<\/b><\/span><\/span>\u00a0tem o <\/b><\/span><\/span>comportamento<\/b><\/span><\/span>\u00a0de um gerador mec\u00e2nico de eletricidade <\/b><\/span><\/span><\/p>\n

\"\"<\/p>\n

\u00a0<\/span>de fem \u03b5\u00a0 \u2014 \u00a0quando voc\u00ea movimenta o condutor RS de comprimento L com velocidade constante, para a direita,\u00a0<\/b><\/span><\/span>voc\u00ea est\u00e1 aumentando<\/b><\/span><\/span>\u00a0a \u00e1rea da espira de \u0394S=y.L, provocando uma varia\u00e7\u00e3o de fluxo magn\u00e9tico\u00a0<\/b><\/span><\/span>que por sua vez<\/b><\/span><\/span>\u00a0faz surgir na espira uma corrente el\u00e9trica induzida\u00a0<\/b><\/span><\/span>e consequentemente<\/b><\/span><\/span>\u00a0uma tens\u00e3o (for\u00e7a eletromotriz induzida)\u00a0 \u2014\u00a0 \u03b5=\u0394\u03a6\/\u0394t\u00a0 \u2014\u00a0\u00a0 a varia\u00e7\u00e3o de fluxo,\u00a0<\/b><\/span><\/span>num campo magn\u00e9tico uniforme<\/b><\/span><\/span>, \u00e9 fornecida por \u0394\u03a6=B.(\u0394S).cos\u03b1\u00a0 \u2014\u00a0 \u0394\u03a6=B.(\u0394S).cos0o\u00a0 \u2014\u00a0\u00a0\u0394\u03a6=B.(\u0394S).1\u00a0 \u2014\u00a0 \u0394\u03a6=B.(y.L)\u00a0 \u2014\u00a0 \u00a0\u03b5=\u0394\u03a6\/\u0394t\u00a0 \u2014\u00a0 \u03b5= B.y.L\/\u0394t\u00a0 \u2014\u00a0 V=\u0394S\/\u0394t=y\/\u0394t\u00a0 \u2014\u00a0\u00a0\u03b5=B.L.V\u00a0\u00a0<\/b><\/span><\/span>\u2014\u00a0 o sentido da corrente el\u00e9trica induzida<\/b><\/span><\/span>\u00a0\u00e9 fornecida pela lei de Lenz \u201ca for\u00e7a eletromotriz induzida e a corrente induzida geram um fluxo magn\u00e9tico que se op\u00f5e \u00e0 varia\u00e7\u00e3o do fluxo causador da indu\u00e7\u00e3o\u201d<\/b><\/span><\/span><\/p>\n

II.\u00a0<\/b><\/span><\/span>Correta\u00a0<\/b><\/span><\/span>\uf0de<\/b><\/span><\/span><\/span>\u00a0Todo campo magn\u00e9tico depende de uma orienta\u00e7\u00e3o, <\/b><\/span><\/span>portanto, <\/b><\/span><\/span>formam sempre dois polos.<\/b><\/span><\/span><\/p>\n

III.<\/b><\/span><\/span>\u00a0Falsa\u00a0<\/b><\/span><\/span>\uf0de<\/b><\/span><\/span><\/span>\u00a0Todo campo magn\u00e9tico depende de uma orienta\u00e7\u00e3o, <\/b><\/span><\/span>portanto, <\/b><\/span><\/span>formam sempre dois polos.<\/b><\/span><\/span><\/p>\n

IV.<\/b><\/span><\/span>\u00a0Falsa\u00a0<\/b><\/span><\/span>\uf0de<\/b><\/span><\/span><\/span>\u00a0Toda for\u00e7a magn\u00e9tica atua\u00a0<\/b><\/span><\/span>somente\u00a0<\/b><\/span><\/span>sobre cargas el\u00e9tricas em movimento.\u00a0<\/b><\/span><\/span>Somente desta forma<\/b><\/span><\/span>\u00a0as cargas acabam possuindo seu pr\u00f3prio campo\u00a0<\/b><\/span><\/span>para ocorrer intera\u00e7\u00e3o.<\/b><\/span><\/span><\/p>\n

R- D<\/b><\/span><\/span><\/span><\/p>\n

20- <\/b><\/span><\/span><\/span>(Lei de Faraday<\/b><\/span><\/span>\u00a0\"\"\u00a0m\u00f3dulo da varia\u00e7\u00e3o de fluxo = for\u00e7a eletromotriz\/intervalo de tempo\u00a0\"\"\u00a0\u0399\u0424I = E\/\u2206t\u00a0\"\"\u00a01Wb\/s = E\/1s\u00a0\"\"\u00a0<\/b><\/span><\/span>E = 1 V<\/b><\/span><\/span><\/span><\/p>\n

21- <\/b><\/span><\/span><\/span>O\u00a0<\/b><\/span><\/span>polo norte<\/b><\/span><\/span>\u00a0do im\u00e3 se\u00a0<\/b><\/span><\/span>afasta da espira ou do solenoide<\/b><\/span><\/span><\/p>\n

A\u00a0<\/b><\/span><\/span>corrente induzida <\/b><\/span><\/span>na espira ou no solenoide deve ter um\u00a0<\/b><\/span><\/span>sentido\u00a0<\/b><\/span><\/span>que vai originar na espira um\u00a0<\/b><\/span><\/span>polo que deve atrair polo norte que se afasta<\/b><\/span><\/span>\u00a0para impedir o afastamento.<\/b><\/span><\/span><\/p>\n

Assim, a\u00a0<\/b><\/span><\/span>face esquerda da espira deve ser um polo sul.<\/b><\/span><\/span><\/p>\n

\"\"<\/p>\n

Sabendo que a\u00a0<\/b><\/span><\/span>face\u00a0<\/b><\/span><\/span>esquerda<\/b><\/span><\/span>\u00a0da espira ou solenoide \u00e9 um\u00a0<\/b><\/span><\/span>polo sul <\/b><\/span><\/span>(onde chegam as linhas de indu\u00e7\u00e3o)<\/b><\/span><\/span>\u00a0e a face\u00a0<\/b><\/span><\/span>direita<\/b><\/span><\/span>\u00a0\u00e9 um\u00a0<\/b><\/span><\/span>polo norte <\/b><\/span><\/span>(de onde saem as linhas de indu\u00e7\u00e3o<\/b><\/span><\/span>), aplica-se a regra\u00a0<\/b><\/span><\/span>da m\u00e3o direita <\/b><\/span><\/span>(polegar no sentido da corrente e a \u201cfechada\u201d da m\u00e3o passando por dentro da espira, fornece o sentido das linhas de indu\u00e7\u00e3o).<\/b><\/span><\/span><\/p>\n

Assim,\u00a0<\/b><\/span><\/span>para que a\u00a0<\/b><\/span><\/span>face esquerda da espira seja um polo sul e a direita um polo norte<\/b><\/span><\/span>, a\u00a0<\/b><\/span><\/span>corrente el\u00e9trica induzida deve ter o sentido das figuras acima.<\/b><\/span><\/span>\u00a0<\/b><\/span><\/span><\/p>\n

Outra maneira de voc\u00ea obter o mesmo sentido para a corrente el\u00e9trica<\/b><\/span><\/span>:<\/b><\/span><\/span><\/span><\/p>\n

O\u00a0<\/b><\/span><\/span>polo sul <\/b><\/span><\/span>do im\u00e3 se <\/b><\/span><\/span>aproxima da espira ou do solenoide<\/b><\/span><\/span><\/p>\n

A\u00a0<\/b><\/span><\/span>corrente induzida<\/b><\/span><\/span>\u00a0deve ter um\u00a0<\/b><\/span><\/span>sentido\u00a0<\/b><\/span><\/span>que vai originar na espira\u00a0<\/b><\/span><\/span>um polo que deve repelir polo sul que se aproxima<\/b><\/span><\/span>, na tentativa de impedir a aproxima\u00e7\u00e3o.<\/b><\/span><\/span><\/p>\n

Assim, a\u00a0<\/b><\/span><\/span>face esquerda da espira deve ser um polo sul.<\/b><\/span><\/span><\/p>\n

\"\"<\/p>\n

Sabendo que\u00a0<\/b><\/span><\/span>a face esquerda da espira \u00e9 um p\u00f3lo sul<\/b><\/span><\/span>(onde chegam as linhas de indu\u00e7\u00e3o)<\/b><\/span><\/span>\u00a0e que a\u00a0<\/b><\/span><\/span>face direita \u00e9 um polo norte <\/b><\/span><\/span>(de onde saem as linhas de indu\u00e7\u00e3o) <\/b><\/span><\/span>aplica-se a\u00a0<\/b><\/span><\/span>regra da m\u00e3o direita (polegar no sentido da corrente e a \u201cfechada\u201d da m\u00e3o passando por dentro da espira, fornece o sentido das linhas de indu\u00e7\u00e3o).<\/b><\/span><\/span><\/p>\n

Assim, para que a\u00a0<\/b><\/span><\/span>face esquerda da espira seja um polo sul e a direita um polo norte<\/b><\/span><\/span>, a\u00a0<\/b><\/span><\/span>corrente el\u00e9trica induzida <\/b><\/span><\/span>deve ter o sentido das figuras acima que \u00e9 o mesmo que da figura do enunciado.<\/b><\/span><\/span><\/p>\n

R- A<\/b><\/span><\/span><\/span><\/p>\n

22- <\/b><\/span><\/span><\/span>
\nFluxo magn\u00e9tico<\/b><\/span><\/span><\/p>\n

Considere uma\u00a0<\/b><\/span><\/span>espira circular, quadrada ou retangular<\/b><\/span><\/span>\u00a0de\u00a0<\/b><\/span><\/span>\u00e1rea S<\/b><\/span><\/span>\u00a0no interior de um campo\u00a0<\/b><\/span><\/span>magn\u00e9tico uniforme de indu\u00e7\u00e3o\"\".<\/b><\/span><\/span>\u00a0Considere\"\"\u00a0o <\/b><\/span><\/span>vetor normal ao plano que cont\u00e9m a espira e \u03b1 o \u00e2ngulo que o vetor indu\u00e7\u00e3o magn\u00e9tica\"\"\u00a0forma com\"\".<\/b><\/span><\/span><\/p>\n

\"\"<\/p>\n

\u00a0<\/span>Define-se\u00a0<\/b><\/span><\/span>fluxo magn\u00e9tico pela letra \u03a6 (fi),<\/b><\/span><\/span>\u00a0como sendo o\u00a0<\/b><\/span><\/span>produto entre o vetor indu\u00e7\u00e3o magn\u00e9tica\"\"<\/b><\/span><\/span>, a\u00a0<\/b><\/span><\/span>\u00e1rea S<\/b><\/span><\/span>\u00a0da espira e o\u00a0<\/b><\/span><\/span>cosseno do \u00e2ngulo\u00a0\u03b1\u00a0formado entre\u00a0\"\"\u00a0 e\u00a0\"\",<\/b><\/span><\/span>\u00a0ou seja:<\/b><\/span><\/span><\/p>\n

\"\"<\/p>\n

For\u00e7a eletromotriz induzida<\/b><\/span><\/span><\/p>\n

\u201c\u00a0<\/span>O\u00a0<\/b><\/span><\/span>m\u00f3dulo da for\u00e7a eletromotriz induzida<\/b><\/span><\/span>\u00a0num circuito \u00e9 igual \u00e0\u00a0<\/b><\/span><\/span>raz\u00e3o entre a varia\u00e7\u00e3o do fluxo magn\u00e9tico nesse circuito, pelo intervalo de tempo em que essa varia\u00e7\u00e3o ocorre\u201d<\/b><\/span><\/span><\/p>\n

\"\"<\/p>\n

\"\"<\/p>\n

\"\"<\/p>\n

23- <\/b><\/span><\/span><\/span>01)<\/b><\/span><\/span>\u00a0Condutores el\u00e9tricos paralelos percorridos por correntes el\u00e9tricas que fluem no mesmo sentido<\/b><\/span><\/span><\/p>\n

repelem-se.<\/b><\/span><\/span><\/p>\n

01. Falsa<\/b><\/span><\/span>\u00a0\"\"\u00a0<\/b><\/span><\/span>For\u00e7a de intera\u00e7\u00e3o entre dois fios condutores paralelos<\/b><\/span><\/span><\/p>\n

\"\"\u00a0<\/span>Considere dois\u00a0<\/b><\/span><\/span>condutores retil\u00edneos 1 e 2<\/b><\/span><\/span>\u00a0percorridos, respectivamente por correntes el\u00e9tricas i1\u00a0e i2,\u00a0e separados por uma dist\u00e2ncia \u00a0d. Tem-se duas situa\u00e7\u00f5es:<\/b><\/span><\/span><\/p>\n

\"\"\u00a0<\/span>As correntes el\u00e9tricas tem mesmo sentido<\/b><\/span><\/span><\/p>\n

\"\"<\/p>\n

Utilizando a regra da m\u00e3o direita, voc\u00ea determina\u00a0\"\"\u00a0que \u00e9 o vetor indu\u00e7\u00e3o magn\u00e9tica que o condutor 1 produz onde est\u00e1 o condutor 2.<\/b><\/span><\/span><\/p>\n

\"\"<\/p>\n

O condutor 2, imerso no campo magn\u00e9tico de\u00a0\"\"\u00a0ficar\u00e1 sujeito a uma for\u00e7a magn\u00e9tica\u00a0\"\", fornecida pela regra da m\u00e3o esquerda.<\/b><\/span><\/span><\/p>\n

\"\"<\/p>\n

Assim, o condutor 2 fica sujeito a uma for\u00e7a magn\u00e9tica\u00a0\"\"\u00a0vertical e para cima.<\/b><\/span><\/span><\/p>\n

Analogamente, o condutor 2 origina, onde est\u00e1 o condutor 1, um campo magn\u00e9tico\u00a0\"\",\u00a0que, fornecido pela regra da m\u00e3o direita estar\u00e1 saindo da folha de papel.\u00a0<\/b><\/span><\/span>Ent\u00e3o surgir\u00e1 sobre o condutor 1 uma for\u00e7a vertical e para baixo, fornecida pela regra da m\u00e3o esquerda.<\/b><\/span><\/span><\/p>\n

Situa\u00e7\u00e3o final:<\/b><\/span><\/span><\/p>\n

\"\"<\/p>\n

Dois fios condutores retil\u00edneos, paralelos e pr\u00f3ximos um do outro, sofrem for\u00e7as de atra\u00e7\u00e3o se as correntes que os percorrem tiverem mesmo sentido.<\/b><\/span><\/span><\/p>\n

\"\"\u00a0<\/span>Se as correntes el\u00e9tricas tiverem\u00a0<\/b><\/span><\/span>sentidos contr\u00e1rios<\/b><\/span><\/span>, procedendo da mesma forma que no item anterior, voc\u00ea observar\u00e1 que os dois fios sofrem for\u00e7a de repuls\u00e3o.<\/b><\/span><\/span><\/p>\n

\"\"<\/p>\n

Dois fios condutores retil\u00edneos, paralelos e pr\u00f3ximos um do outro, sofrem for\u00e7as de repuls\u00e3o se as correntes que os percorrem tiverem sentidos contr\u00e1rios.<\/b><\/span><\/span><\/p>\n

02)<\/b><\/span><\/span>\u00a0A for\u00e7a eletromotriz induzida em uma espira condutora \u00e9 diretamente proporcional \u00e0 varia\u00e7\u00e3o<\/b><\/span><\/span><\/p>\n

temporal do fluxo magn\u00e9tico que atravessa essa espira.<\/b><\/span><\/span><\/p>\n

02. Correta\u00a0\"\"\u00a0<\/b><\/span><\/span>\u201c O m\u00f3dulo da for\u00e7a eletromotriz induzida num circuito \u00e9 igual \u00e0 raz\u00e3o entre a varia\u00e7\u00e3o do fluxo magn\u00e9tico nesse circuito, pelo intervalo de tempo em que essa varia\u00e7\u00e3o ocorre\u201d<\/b><\/span><\/span><\/p>\n

\"\"<\/p>\n

Eventualmente, devido \u00e0 lei de Lenz, que afirma que a for\u00e7a eletromotriz induzida se op\u00f5e \u00e0 varia\u00e7\u00e3o de fluxo, costuma-se escrever a lei de Lenz da seguinte forma:<\/b><\/span><\/span><\/p>\n

\"\"<\/p>\n

04)<\/b><\/span><\/span>\u00a0A for\u00e7a eletromotriz induzida em uma espira condutora \u00e9 inversamente proporcional ao intervalo<\/b><\/span><\/span><\/p>\n

de tempo em que ocorre a varia\u00e7\u00e3o do fluxo magn\u00e9tico que atravessa a espira.<\/b><\/span><\/span><\/p>\n

04. Correta<\/b><\/span><\/span>\u00a0\"\"\u00a0observe na express\u00e3o\u00a0<\/b><\/span><\/span>\u03b5 = \u2206\u0424\/\u2206t<\/b><\/span><\/span>\u00a0que\u00a0<\/b><\/span><\/span>\u03b5 \u00e9 inversamente proporcional a \u2206t.<\/b><\/span><\/span><\/p>\n

08)<\/b><\/span><\/span>\u00a0A corrente el\u00e9trica induzida em um circuito el\u00e9trico produz um campo magn\u00e9tico que permite o aumento do fluxo magn\u00e9tico que a induz.<\/b><\/span><\/span><\/p>\n

08. Falsa<\/b><\/span><\/span>\u00a0\"\"\u00a0Poe produzir tamb\u00e9m uma\u00a0<\/b><\/span><\/span>diminui\u00e7\u00e3o do fluxo magn\u00e9tico.<\/b><\/span><\/span><\/p>\n

16)<\/b><\/span><\/span>\u00a0A varia\u00e7\u00e3o temporal do campo magn\u00e9tico em uma determinada regi\u00e3o do espa\u00e7o provoca o<\/b><\/span><\/span><\/p>\n

aparecimento de um campo el\u00e9trico vari\u00e1vel nessa mesma regi\u00e3o.<\/b><\/span><\/span><\/p>\n

16. Correta<\/b><\/span><\/span><\/p>\n

R- (02 + 04 + 16) = 22<\/b><\/span><\/span><\/span><\/p>\n

 <\/p>\n

Voltar para os exerc\u00edcios<\/span><\/a><\/h3>\n","protected":false},"excerpt":{"rendered":"

Resolu\u00e7\u00e3o Comentada ELETROMAGNETISMO \u2013 2017 \u2013 2016 – 2015 01- ( ) Na\u00a0eletriza\u00e7\u00e3o por atrito, o corpo\u00a0perde el\u00e9trons\u00a0passa a\u00a0ter mais pr\u00f3tons do que possu\u00eda anteriormente\u00a0e, nesse caso,\u00a0fica eletrizado com carga positiva. (F)\u00a0Na\u00a0eletriza\u00e7\u00e3o por atrito, o corpo\u00a0perde el\u00e9trons (cargas negativas), passa a\u00a0ter excesso de pr\u00f3tons (cargas positivas),\u00a0e, nesse caso,\u00a0fica eletrizado com carga positiva. Mas,\u00a0a quantidade de pr\u00f3tons continua a mesma que<\/p>\n","protected":false},"author":1,"featured_media":0,"parent":3328,"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-3330","page","type-page","status-publish","hentry"],"aioseo_notices":[],"_links":{"self":[{"href":"https:\/\/fisicaevestibular.com.br\/novo\/wp-json\/wp\/v2\/pages\/3330","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=3330"}],"version-history":[{"count":2,"href":"https:\/\/fisicaevestibular.com.br\/novo\/wp-json\/wp\/v2\/pages\/3330\/revisions"}],"predecessor-version":[{"id":3332,"href":"https:\/\/fisicaevestibular.com.br\/novo\/wp-json\/wp\/v2\/pages\/3330\/revisions\/3332"}],"up":[{"embeddable":true,"href":"https:\/\/fisicaevestibular.com.br\/novo\/wp-json\/wp\/v2\/pages\/3328"}],"wp:attachment":[{"href":"https:\/\/fisicaevestibular.com.br\/novo\/wp-json\/wp\/v2\/media?parent=3330"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}