{"id":1971,"date":"2016-02-21T17:32:19","date_gmt":"2016-02-21T17:32:19","guid":{"rendered":"http:\/\/fisicaevestibular.com.br\/novo\/?page_id=1971"},"modified":"2024-08-19T18:16:55","modified_gmt":"2024-08-19T18:16:55","slug":"resolucao-comentada-dos-exercicios-de-vestibulares-sobre-forca-eletromotriz-induzida-transformadores","status":"publish","type":"page","link":"https:\/\/fisicaevestibular.com.br\/novo\/eletricidade\/eletromagnetismo\/transformadores-forca-eletromotriz-induzida\/resolucao-comentada-dos-exercicios-de-vestibulares-sobre-forca-eletromotriz-induzida-transformadores\/","title":{"rendered":"For\u00e7a Eletromotriz Induzida \u2013 Transformadores – Resolu\u00e7\u00e3o"},"content":{"rendered":"

Resolu\u00e7\u00e3o comentada dos exerc\u00edcios de vestibulares sobre <\/b><\/span><\/span><\/span><\/p>\n

For\u00e7a Eletromotriz Induzida \u2013 Transformadores<\/b><\/span><\/span><\/span><\/p>\n

01<\/b><\/span><\/span><\/span>–<\/b><\/span><\/span><\/span> <\/b>A corrente est\u00e1 sendo induzida (indu\u00e7\u00e3o eletromagn\u00e9tica) e muda de sentido no \u201cvai e vem\u201d do im\u00e3\u00a0 —\u00a0\u00a0<\/b><\/span><\/span>R- A<\/b><\/span><\/span><\/p>\n

02-<\/b><\/span><\/span><\/span>\u00a0 <\/b><\/span><\/span><\/span>Fluxo inicial\u00a0 —\u00a0 \u03a6<\/b><\/span><\/span>o<\/b><\/span><\/span><\/sub>\u00a0=37.10<\/b><\/span><\/span>-3<\/b><\/span><\/span><\/sup>Wb\u00a0 —\u00a0 fluxo final\u00a0 —\u00a0\u00a0\u00a0 \u03a6=0\u00a0 —\u00a0 varia\u00e7\u00e3o de fluxo\u00a0 —\u00a0 \u0394\u03a6=\u03a6 – \u03a6<\/b><\/span><\/span>o<\/b><\/span><\/span><\/sub>=37.10<\/b><\/span><\/span>-3<\/b><\/span><\/span><\/sup>\u00a0\u2013 0\u00a0 —\u00a0 \u0394\u03a6=37.10<\/b><\/span><\/span>-3<\/b><\/span><\/span><\/sup>Wb\u00a0 —\u00a0 \u03b5=\u0394\u03a6\/\u0394t=37.10<\/b><\/span><\/span>-3<\/b><\/span><\/span><\/sup>\/10<\/b><\/span><\/span>-3<\/b><\/span><\/span><\/sup>\u00a0 —\u00a0<\/b><\/span><\/span>\u00a0\u03b5=37V<\/b><\/span><\/span><\/p>\n

03-<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/span>01. Correta\u00a0 —\u00a0 quando a espira gira, o fluxo magn\u00e9tico atrav\u00e9s dela sofre varia\u00e7\u00e3o e surge uma for\u00e7a eletromotriz induzida que gera uma corrente el\u00e9trica induzida.<\/b><\/span><\/span><\/p>\n

02. Correta\u00a0 —\u00a0 Lei de Lenz<\/b><\/span><\/span><\/p>\n

O4.<\/b><\/span><\/span><\/span> <\/b>Correta\u00a0 —\u00a0 veja teoria<\/b><\/span><\/span><\/p>\n

08. Falsa\u00a0 —\u00a0 com a espira parada n\u00e3o ocorre varia\u00e7\u00e3o de fluxo magn\u00e9tico.<\/b><\/span><\/span><\/p>\n

16. Correta\u00a0 —\u00a0 \u03a6=B.S.cos\u03b1\u00a0 —\u00a0 \u00a0valor m\u00e1ximo\u00a0 —\u00a0 \u03a6=B.S.cos0<\/b><\/span><\/span>o<\/b><\/span><\/span><\/sup>=2.10<\/b><\/span><\/span>-2<\/b><\/span><\/span><\/sup>.1.10<\/b><\/span><\/span>-3<\/b><\/span><\/span><\/sup>.(+1)=+2,0.10<\/b><\/span><\/span>-5<\/b><\/span><\/span><\/sup>T.m<\/b><\/span><\/span>2<\/b><\/span><\/span><\/sup>\u00a0 —\u00a0 valor m\u00ednimo\u00a0 —\u00a0 \u03a6=B.S.cos\u03b1=2.10<\/b><\/span><\/span>-2<\/b><\/span><\/span><\/sup>.1.10<\/b><\/span><\/span>-3<\/b><\/span><\/span><\/sup>.cos180<\/b><\/span><\/span>o<\/b><\/span><\/span><\/sup>=2.10<\/b><\/span><\/span>-5<\/b><\/span><\/span><\/sup>.(-1)=-2,0.10<\/b><\/span><\/span>-5<\/b><\/span><\/span><\/sup>T.m<\/b><\/span><\/span>2<\/b><\/span><\/span><\/sup>\u00a0 —\u00a0\u00a0<\/b><\/span><\/span>R- (01 + 02\u00a0 04 + 16) = 23<\/b><\/span><\/span><\/p>\n

04-\u00a0<\/b><\/span><\/span>L=10cm=0,1m\u00a0 —\u00a0 S=L.L=0,1.0,1=0,01m<\/b><\/span><\/span>2<\/b><\/span><\/span><\/sup>\u00a0 —\u00a0 \u03a6<\/b><\/span><\/span>i<\/b><\/span><\/span><\/sub>=0\u00a0 —\u00a0 \u03a6<\/b><\/span><\/span>f<\/b><\/span><\/span><\/sub>=B.S=1.0,01=0,01T\u00a0 —\u00a0\u00a0<\/b><\/span><\/span>\u0394<\/b><\/span><\/span><\/span>\u03a6= \u03a6<\/b><\/span><\/span>f\u00a0<\/b><\/span><\/span><\/sub>\u00a0– \u03a6<\/b><\/span><\/span>i<\/b><\/span><\/span><\/sub>=0,01 \u2013 0=0,01T\u00a0 —<\/b><\/span><\/span><\/p>\n

\u03b5=<\/b><\/span><\/span>\u0394<\/b><\/span><\/span><\/span>\u03a6\/<\/b><\/span><\/span>\u0394<\/b><\/span><\/span><\/span>t=0,01\/2\u00a0 —\u00a0 \u03b5=0,005V\u00a0 —\u00a0 R=U\/i\u00a0 —\u00a0 R=\u03b5\/i\u00a0 —\u00a0 0,2=0,005\/i\u00a0 —\u00a0 i=0,025\u00aa\u00a0 —\u00a0\u00a0<\/b><\/span><\/span>i=25mA<\/b><\/span><\/span>\u00a0<\/b><\/span><\/span><\/p>\n

05-<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/span>\u03b5=BLV\u00a0 —\u00a0 3.10<\/b><\/span><\/span>-3<\/b><\/span><\/span><\/sup>=B.2.60\u00a0 —\u00a0\u00a0<\/b><\/span><\/span>B=2,5.10<\/b><\/span><\/span>-5<\/b><\/span><\/span><\/sup>T<\/b><\/span><\/span><\/p>\n

06-<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/span>No intervalo d, onde\u00a0\"\"\u00a0varia, e consequentemente o fluxo magn\u00e9tico tamb\u00e9m varia\u00a0 —\u00a0 R<\/b><\/span><\/span>– E<\/b><\/span><\/span><\/p>\n

07-<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/span>\u03b5=\u0394\u03a6\/\u0394t=2\/1\u00a0 —\u00a0 \u03b5=2V\u00a0 —\u00a0 R=U\/i\u00a0 —\u00a0 R=\u03b5\/i\u00a0 —\u00a0 4=2\/i\u00a0 —\u00a0<\/b><\/span><\/span>\u00a0i=0,5A<\/b><\/span><\/span><\/p>\n

08-<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/span>I \u2013 Como a \u00e1rea das espiras est\u00e1 aumentando (fluxos induzido e indutor tem sentidos contr\u00e1rios) e o fluxo induzido pela corrente est\u00e1 saindo da p\u00e1gina (regra da m\u00e3o direita), o fluxo indutor est\u00e1 entrando na p\u00e1gina\u00a0 —\u00a0 Correta<\/b><\/span><\/span>\"\"<\/p>\n

II \u2013 Correta\u00a0 —\u00a0\u00a0 mesmo campo magn\u00e9tico que o da 1, \u00e1reas aumentando e consequentemente mesmo sentido de corrente.<\/b><\/span><\/span><\/p>\n

III \u2013 Falsa\u00a0 —\u00a0 as express\u00f5es (\u03a6=B.S.cos\u03b1 e \u03b5=\u0394\u03a6\/\u0394t) mostra que a fem induzida depende da \u00e1rea S.<\/b><\/span><\/span><\/p>\n

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

09-<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/span>a) P<\/b><\/span><\/span>total<\/b><\/span><\/span><\/sub>=F\/A=P\/A=mg\/A\u00a0 —\u00a0 P<\/b><\/span><\/span>total<\/b><\/span><\/span><\/sub>=2,16.10<\/b><\/span><\/span>5<\/b><\/span><\/span><\/sup>.10\/(0,5).(0,5)\u00a0 —\u00a0 P<\/b><\/span><\/span>total<\/b><\/span><\/span><\/sub>=86,4.10<\/b><\/span><\/span>5<\/b><\/span><\/span><\/sup>N\/m<\/b><\/span><\/span>2<\/b><\/span><\/span><\/sup>\u00a0 —\u00a0 um suporte\u00a0 —\u00a0 P=86,4.10<\/b><\/span><\/span>5<\/b><\/span><\/span><\/sup>\/12\u00a0 —\u00a0\u00a0<\/b><\/span><\/span>P=7,2.10<\/b><\/span><\/span>5<\/b><\/span><\/span><\/sup>N\/m<\/b><\/span><\/span>2<\/b><\/span><\/span><\/sup><\/p>\n

b) Varia\u00e7\u00e3o de fluxo de 1 espira \u03a6<\/b><\/span><\/span>f<\/b><\/span><\/span><\/sub>=B.S=1,5.10<\/b><\/span><\/span>-2<\/b><\/span><\/span><\/sup>.\u03c0.R<\/b><\/span><\/span>2<\/b><\/span><\/span><\/sup>=1,5.10<\/b><\/span><\/span>-2<\/b><\/span><\/span><\/sup>.3.4\u00a0 —\u00a0 \u03a6<\/b><\/span><\/span>f<\/b><\/span><\/span><\/sub>=18.10<\/b><\/span><\/span>-2<\/b><\/span><\/span><\/sup>Wb\u00a0 —\u00a0 \u03a6<\/b><\/span><\/span>i<\/b><\/span><\/span><\/sub>=0\u00a0 —\u00a0 \u0394\u03a6=18.10<\/b><\/span><\/span>-2<\/b><\/span><\/span><\/sup>Wb\u00a0 —\u00a0 for\u00e7a eletromotriz de uma espira\u00a0 —\u00a0 \u03b5= \u0394\u03a6\/\u0394t=18.10<\/b><\/span><\/span>-2<\/b><\/span><\/span><\/sup>\/5.10<\/b><\/span><\/span>-2<\/b><\/span><\/span><\/sup>=3,6V\u00a0 —\u00a0 uma espira \u2013 \u03b5=3,6V\u00a0 —\u00a0 10.000espiras\u00a0 —\u00a0<\/b><\/span><\/span>\u00a0\u03b5=3,6.10<\/b><\/span><\/span>4<\/b><\/span><\/span><\/sup>V<\/b><\/span><\/span><\/p>\n

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

11-<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/span>S=0,2.0,3\u00a0 —\u00a0 S=0,06m<\/b><\/span><\/span>2<\/b><\/span><\/span><\/sup>\u00a0 — \u00a0intervalo I\u00a0 —\u00a0 \u0394\u03a6=(6.0,06 \u2013 0.0,06)=0,36Wb\u00a0 —\u00a0 \u03b5= \u0394\u03a6\/\u0394t=0,36\/0,3\u00a0 —\u00a0 \u03b5=1,2V\u00a0 —\u00a0 R=\u03b5\/i\u00a0 —\u00a0 3=1,2\/i\u00a0 —\u00a0<\/b><\/span><\/span>\u00a0i<\/b><\/span><\/span>I<\/b><\/span><\/span><\/sub>=0,4 A<\/b><\/span><\/span>\u00a0 —\u00a0 intervalo II\u00a0 —\u00a0 \u0394\u03a6=(6.0,06 \u2013 6.0,06)=0,0\u00a0 —\u00a0 \u03b5= \u0394\u03a6\/\u0394t=0,0\/0,3\u00a0 —\u00a0 \u03b5=0\u00a0 —\u00a0\u00a0<\/b><\/span><\/span>i<\/b><\/span><\/span>II<\/b><\/span><\/span><\/sub>=0<\/b><\/span><\/span>\u00a0 —\u00a0\u00a0 intervalo III\u00a0 —\u00a0 \u0394\u03a6=(0.0,06 \u2013 0,6.0,06)= – 0,36Wb\u00a0 —\u00a0 \u03b5=\u00a0<\/b><\/span><\/span>\u05c0<\/span><\/span><\/span><\/span><\/span>\u0394\u03a6<\/b><\/span><\/span>\u05c0<\/span><\/span><\/span><\/span><\/span>\/\u0394t=0,36\/0,6\u00a0 —\u00a0 \u03b5=0,6V\u00a0 —\u00a0 R=\u03b5\/i\u00a0 —\u00a0 3=0,6\/i\u00a0 —\u00a0<\/b><\/span><\/span>\u00a0i<\/b><\/span><\/span>III<\/b><\/span><\/span><\/sub>=0,2 A<\/b><\/span><\/span>\u00a0 —\u00a0\u00a0<\/b><\/span><\/span>R- B<\/b><\/span><\/span><\/p>\n

12-<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/span>S=0,10.0,10=0,01m<\/b><\/span><\/span>2<\/b><\/span><\/span><\/sup>\u00a0 —\u00a0 varia\u00e7\u00e3o de fluxo entre 0 e 16.10<\/b><\/span><\/span>-3<\/b><\/span><\/span><\/sup>s\u00a0 —\u00a0 \u0394\u03a6=8.10<\/b><\/span><\/span>-3<\/b><\/span><\/span><\/sup>\u00a0\u2013 0=8.10<\/b><\/span><\/span>-3<\/b><\/span><\/span><\/sup>Wb\u00a0 —\u00a0 \u03b5= \u0394\u03a6\u0394t=8.10<\/b><\/span><\/span>-3<\/b><\/span><\/span><\/sup>16.10<\/b><\/span><\/span>-3<\/b><\/span><\/span><\/sup>\u00a0 —\u00a0 \u03b5=0,5V\u00a0 —\u00a0 R=\u03b5i\u00a0 —\u00a0 20=0,5\/i\u00a0 —\u00a0 i=0,025 A\u00a0 —\u00a0\u00a0<\/b><\/span><\/span>\u00a0R- D<\/b><\/span><\/span><\/p>\n

13-<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/span>\u03b5=B.L.V=4.0,02.0,2\u00a0 —\u00a0 \u03b5=0,016V\u00a0 —\u00a0\u00a0<\/b><\/span><\/span>\u03b5=1,6.10<\/b><\/span><\/span>-2<\/b><\/span><\/span><\/sup>V\u00a0<\/b><\/span><\/span>\u00a0—\u00a0 como o fluxo atrav\u00e9s da espira est\u00e1 aumentando, o fluxo induzido deve se opor a esse aumento e o campo magn\u00e9tico induzido deve estar saindo do papel\u00a0 —\u00a0 usando a regra da m\u00e3o direita com\"\"\u00a0saindo do papel, a corrente el\u00e9trica induzida ser\u00e1 no\u00a0<\/b><\/span><\/span>sentido anti-hor\u00e1rio.<\/b><\/span><\/span><\/p>\n

14-<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/span>Fluxo total atrav\u00e9s da bobina\u00a0 —\u00a0 \u03a6<\/b><\/span><\/span>total<\/b><\/span><\/span><\/sub>=nB.S=20.0,2.25.10<\/b><\/span><\/span>-6<\/b><\/span><\/span><\/sup>\u00a0 —\u00a0 \u03a6<\/b><\/span><\/span>total<\/b><\/span><\/span><\/sub>=100.10<\/b><\/span><\/span>-6<\/b><\/span><\/span><\/sup>=10<\/b><\/span><\/span>-4<\/b><\/span><\/span><\/sup>Wb\u00a0 —\u00a0\u00a0 a velocidade escalar de um ponto da periferia da roda\u00a0 de raio R=60\/2=30=0,3m, \u00e9 V=36km\/h=10m\/s<\/b><\/span><\/span><\/p>\n

—\u00a0 velocidade angular da roda da roda\u00a0 —\u00a0 W=V\/R=10\/0,3\u00a0 —\u00a0 W=100\/3rad\/s\u00a0 —\u00a0 esta velocidade angular \u00e9 a mesma onde est\u00e3o os im\u00e3s de raio R=0,15m\u00a0 —\u00a0 W=V\/R\u00a0 —\u00a0 100\/3=V\/0,15m\u00a0 — V=5m\/s (velocidade escalar dos im\u00e3s)\u00a0 —\u00a0 \u0394S=um dos lados da espira quadrada de \u00e1rea 25mm<\/b><\/span><\/span>2<\/b><\/span><\/span><\/sup>\u00a0 —\u00a0 L=5mm=5.10<\/b><\/span><\/span>-3<\/b><\/span><\/span><\/sup>\u00a0 —\u00a0 V= \u0394S\/\u0394t\u00a0 —\u00a0 5=5.10<\/b><\/span><\/span>-3<\/b><\/span><\/span><\/sup>\/\u0394t\u00a0 —\u00a0 \u0394t=10<\/b><\/span><\/span>-3<\/b><\/span><\/span><\/sup>s (tempo que a bobina demora para variar o fluxo de 0 at\u00e9 o valor m\u00e1ximo)\u00a0 —\u00a0 fem m\u00e1xima\u00a0 —\u00a0 \u03b5=\u0394\u03a6\/\u0394t=10<\/b><\/span><\/span>-4<\/b><\/span><\/span><\/sup>\/10<\/b><\/span><\/span>-3<\/b><\/span><\/span><\/sup>\u00a0 —\u00a0 \u03b5=10<\/b><\/span><\/span>-1<\/b><\/span><\/span><\/sup>V\u00a0 —\u00a0\u00a0<\/b><\/span><\/span>R- D<\/b><\/span><\/span>\"\"<\/p>\n

15- R- A<\/b><\/span><\/span>\u00a0\u2013 Veja teoria<\/b><\/span><\/span><\/p>\n

16-\u00a0<\/b><\/span><\/span>S=\u03c0R<\/b><\/span><\/span>2<\/b><\/span><\/span><\/sup>=3.(2.10<\/b><\/span><\/span>-2<\/b><\/span><\/span><\/sup>)<\/b><\/span><\/span>2<\/b><\/span><\/span><\/sup>\u00a0 —\u00a0 S=12.10<\/b><\/span><\/span>-4<\/b><\/span><\/span><\/sup>m<\/b><\/span><\/span>2<\/b><\/span><\/span><\/sup>\u00a0 —\u00a0 entre 0 e 5.10<\/b><\/span><\/span>-2<\/b><\/span><\/span><\/sup>s\u00a0 —\u00a0 \u0394\u03a6=B.S \u2013 B<\/b><\/span><\/span>o<\/b><\/span><\/span><\/sub>.S<\/b><\/span><\/span>o<\/b><\/span><\/span><\/sub>=5.10<\/b><\/span><\/span>-4<\/b><\/span><\/span><\/sup>.12.10<\/b><\/span><\/span>-4<\/b><\/span><\/span><\/sup>\u00a0\u2013 0=6.10<\/b><\/span><\/span>-7<\/b><\/span><\/span><\/sup>Wb\u00a0 —\u00a0 \u03b5= \u0394\u03a6\/\u0394t= 6.10<\/b><\/span><\/span>-7<\/b><\/span><\/span><\/sup>\/5.10<\/b><\/span><\/span>-2<\/b><\/span><\/span><\/sup>\u00a0 —\u00a0 \u03b5=1,2.10<\/b><\/span><\/span>-5<\/b><\/span><\/span><\/sup>V\u00a0 —\u00a0<\/b><\/span><\/span>\u00a0\u03b5=12\u03bcV<\/b><\/span><\/span><\/p>\n

17-<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/span>De acordo com a Lei de Faraday-Lenz, o deslocamento da barra met\u00e1lica, levando \u00e0 varia\u00e7\u00e3o do fluxo magn\u00e9tico atrav\u00e9s da \u00e1rea delimitada pela barra met\u00e1lica e pelos trilhos, gera uma for\u00e7a eletromotriz no circuito. Por outro lado, na medida em que a barra met\u00e1lica \u00e9 percorrida por uma corrente el\u00e9trica e est\u00e1 situada em uma regi\u00e3o em que h\u00e1 campo magn\u00e9tico, sobre ela atuar\u00e1 uma for\u00e7a magn\u00e9tica. A for\u00e7a eletromotriz gerada se contrap\u00f5e ao efeito que a gera e desse modo a for\u00e7a magn\u00e9tica que atua sobre a barra met\u00e1lica \u00e9 contr\u00e1ria \u00e0 tens\u00e3o no fio ao qual est\u00e1 conectada a massa M.<\/b><\/span><\/span><\/p>\n

A for\u00e7a eletromotriz gerada \u00e9 dada por \u03b5<\/b><\/span><\/span>\uf020<\/b><\/span><\/span>= Blv, em que v \u00e9 a velocidade da barra met\u00e1lica e a for\u00e7a magn\u00e9tica sobre a barra \u00e9<\/b><\/span><\/span><\/p>\n

F<\/b><\/span><\/span>m<\/b><\/span><\/span><\/sub>\u00a0= P\u00a0 —\u00a0 Bil=mg\u00a0 —\u00a0 0,2=i.1=0,04.10\u00a0 —\u00a0 i=2A\u00a0 —\u00a0 R=U\/i=\u03b5\/i \u00a0—\u00a0 0,5=\u03b5\/2\u00a0 —\u00a0 \u03b5=1V\u00a0 —\u00a0 \u03b5=BLV\u00a0 —\u00a0 1=0,2.1.V\u00a0 —\u00a0\u00a0<\/b><\/span><\/span>V=5m\/s<\/b><\/span><\/span><\/p>\n

18-<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/span>A corrente i na barra tem sentido de M para N e aplicando a regra da m\u00e3o esquerda voc\u00ea descobre que a for\u00e7a magn\u00e9tica sobre a barra \u00e9 para a esquerda e ela se move nessa dire\u00e7\u00e3o e sentido com acelera\u00e7\u00e3o constante j\u00e1 que a for\u00e7a \u00e9 constante\u00a0 —\u00a0\u00a0<\/b><\/span><\/span>R- E<\/b><\/span><\/span>\"\"<\/p>\n

19-<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/span>Quando a velocidade da barra se tornar constante ela estar\u00e1 em equil\u00edbrio din\u00e2mico e a resultante sobre ela ser\u00e1 nula\u00a0 —\u00a0 decompondo a for\u00e7a peso da barra na dire\u00e7\u00e3o do movimento\u00a0 —\u00a0 P<\/b><\/span><\/span>p<\/b><\/span><\/span><\/sub>=Psen30<\/b><\/span><\/span>o<\/b><\/span><\/span><\/sup>=mgsen30<\/b><\/span><\/span>o=<\/b><\/span><\/span><\/sup>=5.10.0,5\u00a0 —\u00a0 P<\/b><\/span><\/span>p<\/b><\/span><\/span><\/sub>=25N\u00a0 —\u00a0 essa for\u00e7a \u00e9 equilibrada pela for\u00e7a magn\u00e9tica perpendicular ao plano da espira de intensidade\u00a0 —\u00a0 F<\/b><\/span><\/span>m<\/b><\/span><\/span><\/sub>=BiLsen90<\/b><\/span><\/span>o<\/b><\/span><\/span><\/sup>=Bi1.1\u00a0 —\u00a0 F<\/b><\/span><\/span>m<\/b><\/span><\/span><\/sub>=Bi\u00a0 —\u00a0<\/b><\/span><\/span><\/p>\n

F<\/b><\/span><\/span>m<\/b><\/span><\/span><\/sub>=P<\/b><\/span><\/span>p<\/b><\/span><\/span><\/sub>\u00a0 —\u00a0 Bi=25 (I)\u00a0 —\u00a0 a fem induzida no circuito vale\u00a0 —\u00a0 \u03b5=BLV\u00a0 —\u00a0 R=\u03b5\/i\u00a0 —\u00a0 \u03b5=Ri\u00a0 —\u00a0 Ri=BLV\u00a0 —\u00a0 2.i=B.1.2\u00a0 —\u00a0 B=i (II)\u00a0 —\u00a0 II em I\u00a0 —\u00a0 B.B=25\u00a0 —\u00a0 B<\/b><\/span><\/span>2<\/b><\/span><\/span><\/sup>=25\u00a0 —\u00a0 B=5T\u00a0 —\u00a0<\/b><\/span><\/span>R- E<\/b><\/span><\/span><\/p>\n

20-<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/span>O alum\u00ednio \u00e9 um material Paramagn\u00e9tico, ou seja, fracamente atra\u00eddo pelo \u00edm\u00e3. Como est\u00e1 eq\u00fcidistante dos p\u00f3los do \u00edm\u00e3 a for\u00e7a resultante no anel no eixo N – S \u00e9 nula. Por\u00e9m, o fluxo de linhas de indu\u00e7\u00e3o no interior do anel \u00e9 vari\u00e1vel e cria uma pequena corrente induzida e consequentemente uma for\u00e7a eletromotriz induzida. Ent\u00e3o, passam a agir sobre o anel for\u00e7as magn\u00e9ticas que se op\u00f5es ao movimento, diminuindo lentamente a oscila\u00e7\u00e3o\u00a0 —<\/b><\/span><\/span>\u00a0R- A<\/b><\/span><\/span><\/p>\n

21-<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/span>\u0394\u03a6= \u03a6<\/b><\/span><\/span>2\u00a0<\/b><\/span><\/span><\/sub>– \u03a6<\/b><\/span><\/span>1<\/b><\/span><\/span><\/sub>=2,3.10<\/b><\/span><\/span>-3<\/b><\/span><\/span><\/sup>\u00a0\u2013 0,3.10<\/b><\/span><\/span>-3<\/b><\/span><\/span><\/sup>\u00a0 —\u00a0 \u0394\u03a6=2,0.10<\/b><\/span><\/span>-3<\/b><\/span><\/span><\/sup>Wb\u00a0 —\u00a0 \u03b5=\u00a0<\/b><\/span><\/span>\u05c0<\/span><\/span><\/span><\/span><\/span>\u0394\u03a6<\/b><\/span><\/span>\u05c0<\/span><\/span><\/span><\/span><\/span>\u0394t=2.10<\/b><\/span><\/span>-3<\/b><\/span><\/span><\/sup>\/0,5\u00a0 —\u00a0 \u03b5=4.10<\/b><\/span><\/span>-3<\/b><\/span><\/span><\/sup>V\u00a0 —\u00a0 R=\u03b5\/i\u00a0 —\u00a0 1=4.10<\/b><\/span><\/span>-3<\/b><\/span><\/span><\/sup>\/i\u00a0 —\u00a0\u00a0<\/b><\/span><\/span><\/p>\n

R-\u00a0<\/b><\/span><\/span>i=4mA<\/b><\/span><\/span><\/p>\n

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

\u00a0<\/span>Entre 0 e 4s\u00a0 —\u00a0 \u03b5=\u0394\u03a6\/\u0394t=(B<\/b><\/span><\/span>f<\/b><\/span><\/span><\/sub>S<\/b><\/span><\/span>f<\/b><\/span><\/span><\/sub>\u00a0\u2013 B<\/b><\/span><\/span>o<\/b><\/span><\/span><\/sub>S<\/b><\/span><\/span>o<\/b><\/span><\/span><\/sub>)\/\u0394t=(2.0,5 \u2013 0.0,5)\/4\u00a0 —\u00a0\u00a0<\/b><\/span><\/span>\u03b5<\/b><\/span><\/span>1<\/b><\/span><\/span><\/sub>=0,25V<\/b><\/span><\/span>\u00a0 —\u00a0 Entre 4s e 6s\u00a0 —\u00a0 \u03b5=\u0394\u03a6\/\u0394t=(B<\/b><\/span><\/span>f<\/b><\/span><\/span><\/sub>S<\/b><\/span><\/span>f<\/b><\/span><\/span><\/sub>\u00a0\u2013 B<\/b><\/span><\/span>o<\/b><\/span><\/span><\/sub>S<\/b><\/span><\/span>o<\/b><\/span><\/span><\/sub>)\/\u0394t=(2.0,5 \u2013 2.0,5)\/4\u00a0 —\u00a0\u00a0<\/b><\/span><\/span>\u03b5<\/b><\/span><\/span>2<\/b><\/span><\/span><\/sub>=0<\/b><\/span><\/span>\u00a0 —\u00a0 Entre 6s e 8s\u00a0 —\u00a0 \u03b5=\u0394\u03a6\/\u0394t=(B<\/b><\/span><\/span>f<\/b><\/span><\/span><\/sub>S<\/b><\/span><\/span>f<\/b><\/span><\/span><\/sub>\u00a0\u2013 B<\/b><\/span><\/span>o<\/b><\/span><\/span><\/sub>S<\/b><\/span><\/span>o<\/b><\/span><\/span><\/sub>)\/\u0394t=(-2.0,5 \u2013 2.0,5)\/4\u00a0 —\u00a0\u00a0<\/b><\/span><\/span>\u03b5<\/b><\/span><\/span>3<\/b><\/span><\/span><\/sub>= -1,0V<\/b><\/span><\/span>\u00a0 —\u00a0 Entre 8s e 11s\u00a0 —\u00a0 \u03b5=\u0394\u03a6\/\u0394t=(B<\/b><\/span><\/span>f<\/b><\/span><\/span><\/sub>S<\/b><\/span><\/span>f<\/b><\/span><\/span><\/sub>\u00a0\u2013 B<\/b><\/span><\/span>o<\/b><\/span><\/span><\/sub>S<\/b><\/span><\/span>o<\/b><\/span><\/span><\/sub>)\/\u0394t=(0.0,5 \u2013 (-2.0,5)\/3\u00a0 —\u00a0\u00a0<\/b><\/span><\/span>\u03b5<\/b><\/span><\/span>4<\/b><\/span><\/span><\/sub>= 0,33V<\/b><\/span><\/span>\"\"<\/p>\n

23-<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/span>Quando t=0\u00a0 —\u00a0 \u03a6<\/b><\/span><\/span>o<\/b><\/span><\/span><\/sub>=0\u00a0 —\u00a0 quando t=4s\u00a0 —\u00a0 \u03a6=B.S=4.4.10<\/b><\/span><\/span>-2<\/b><\/span><\/span><\/sup>Wb\u00a0 —\u00a0 \u03b5=\u0394\u03a6\/\u0394t=(16.10<\/b><\/span><\/span>-2<\/b><\/span><\/span><\/sup>\u00a0\u2013 0)\/2\u00a0 —\u00a0 \u03b5=8.10<\/b><\/span><\/span>-2<\/b><\/span><\/span><\/sup>V\u00a0 —\u00a0 esta \u00e9 a fem criada por uma espira\u00a0 —\u00a0 como s\u00e3o 100 espiras\u00a0 —\u00a0 \u03b5=100.8.10<\/b><\/span><\/span>-2<\/b><\/span><\/span><\/sup>\u00a0 —\u00a0<\/b><\/span><\/span>\u00a0\u03b5=8V<\/b><\/span><\/span><\/p>\n

24-<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/span>\u00c1rea do aro\u00a0 —\u00a0 S=\u03c0R<\/b><\/span><\/span>2<\/b><\/span><\/span><\/sup>=3.(0,4)<\/b><\/span><\/span>2<\/b><\/span><\/span><\/sup>\u00a0 — \u00a0S=0,48m<\/b><\/span><\/span>2<\/b><\/span><\/span><\/sup>\u00a0 —\u00a0 fluxo inicial \u2013 \u03a6<\/b><\/span><\/span>o<\/b><\/span><\/span><\/sub>=0\u00a0 —\u00a0 fluxo final \u2013 \u03a6=B.S.cos0<\/b><\/span><\/span>o<\/b><\/span><\/span><\/sup>=1,0.0,48.1\u00a0 —\u00a0 \u03a6=0,48Wb\u00a0 —\u00a0 \u0394\u03a6=(\u03a6 \u2013 \u03a6<\/b><\/span><\/span>o<\/b><\/span><\/span><\/sub>)=0,48Wb\u00a0 —\u00a0 fem induzida\u00a0 —\u00a0 \u03b5=\u0394\u03a6\/\u0394t=0,48\/0,4\u00a0 —\u00a0<\/b><\/span><\/span>\u00a0\u03b5=1,2V<\/b><\/span><\/span><\/p>\n

25-<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/span>R=4\/2cm=2.10<\/b><\/span><\/span>-2<\/b><\/span><\/span><\/sup>m\u00a0 —\u00a0 S=\u03c0R<\/b><\/span><\/span>2<\/b><\/span><\/span><\/sup>=3.4.10<\/b><\/span><\/span>-4<\/b><\/span><\/span><\/sup>\u00a0= 12.10<\/b><\/span><\/span>-4<\/b><\/span><\/span><\/sup>m<\/b><\/span><\/span>2<\/b><\/span><\/span><\/sup>\u00a0 — \u0394\u03a6=B.S=10<\/b><\/span><\/span>3<\/b><\/span><\/span><\/sup>.12.10<\/b><\/span><\/span>-4<\/b><\/span><\/span><\/sup>=1,2Wb\u00a0 —\u00a0 \u03b5=\u0394\u03a6\/\u0394t=1,2\/1\u00a0 —\u00a0 \u03b5=1,2Wb\/s\u00a0 —\u00a0 \u03b5=1,2V\u00a0 —\u00a0 este valor \u00e9 de uma espira\u00a0 —\u00a0 para 30.000 espiras\u00a0 —\u00a0 \u03b5=3.10<\/b><\/span><\/span>4<\/b><\/span><\/span><\/sup>.1,2\u00a0 —\u00a0\u00a0<\/b><\/span><\/span>\u03b5=36.000V<\/b><\/span><\/span><\/p>\n

26-<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/span>As asas do avi\u00e3o se comportam como se fossem um condutor retil\u00edneo em movimento, atravessando o campo magn\u00e9tico da Terra e consequentemente induzindo uma for\u00e7a eletromotriz (diferen\u00e7a de potencial) entre os extremos de suas asas\u00a0 —\u00a0<\/b><\/span><\/span>\u00a0R- E\u00a0<\/b><\/span><\/span>\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/b><\/span><\/span><\/p>\n

27-<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/span>As asas do avi\u00e3o se comportam como se fossem um condutor retil\u00edneo em movimento, atravessando o campo magn\u00e9tico da Terra e consequentemente induzindo uma for\u00e7a eletromotriz entre os extremos de suas asas\u00a0 —\u00a0 \u03b5=BVL=5.10<\/b><\/span><\/span>-5<\/b><\/span><\/span><\/sup>.200.60\u00a0 —\u00a0<\/b><\/span><\/span><\/p>\n

\u03b5=60.000.10<\/b><\/span><\/span>-5<\/b><\/span><\/span><\/sup>\u00a0 —\u00a0\u00a0<\/b><\/span><\/span>\u03b5=0,6V<\/b><\/span><\/span>\u00a0<\/b><\/span><\/span><\/p>\n

28-<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/span>A corrente el\u00e9trica induzida \u00e9 uma fun\u00e7\u00e3o senoidal do tempo e \u00e9 alternada porque ela percorre a espira ou bobina invertendo seu sentido durante um ciclo, como indica o gr\u00e1fico i X t.<\/b><\/span><\/span>\"\"<\/p>\n

Observe na seq\u00fc\u00eancia do enunciado que, quando t=o o fluxo e consequentemente a corrente s\u00e3o m\u00e1ximos e que o ciclo se completa quando t=8s.<\/b><\/span><\/span><\/p>\n

29-<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/span>a) Pot\u00eancia do LED\u00a0 —\u00a0 P=i.U\u00a0 —\u00a0 24.10<\/b><\/span><\/span>-3<\/b><\/span><\/span><\/sup>=20.10<\/b><\/span><\/span>-3<\/b><\/span><\/span><\/sup>.U\u00a0 —\u00a0<\/b><\/span><\/span>\u00a0U=1,2V<\/b><\/span><\/span><\/p>\n

b) \u0394\u03a6=B.\u0394S=1,1.0,4.0,6\u00a0 —\u00a0\u00a0<\/b><\/span><\/span>\u0394\u03a6=0,264Wb<\/b><\/span><\/span><\/p>\n

c) V=<\/b><\/span><\/span>\u05c0<\/span><\/span><\/span><\/span><\/span>\u03b5<\/b><\/span><\/span>\u05c0<\/span><\/span><\/span><\/span><\/span>= \u0394\u03a6\/\u0394t\u00a0 —\u00a0 1,2=0,264\/\u0394t\u00a0 —\u00a0\u00a0<\/b><\/span><\/span>\u0394t=0,22s<\/b><\/span><\/span><\/p>\n

30-<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/span>a) B=\u03bc<\/b><\/span><\/span>o<\/b><\/span><\/span><\/sub>i \/2\u03c0 r\u00a0 —\u00a0 10<\/b><\/span><\/span>-5<\/b><\/span><\/span><\/sup>=4.\u03c010<\/b><\/span><\/span>-7<\/b><\/span><\/span><\/sup>.i\/2\u03c0.2,5.10<\/b><\/span><\/span>-2<\/b><\/span><\/span><\/sup>\u00a0 —\u00a0<\/b><\/span><\/span>\u00a0i=1,25A<\/b><\/span><\/span><\/p>\n

b) \u03b5= -\u0394\u03a6\/\u0394t\u00a0 —\u00a0 \u0394\u03a6= \u0394B.A=(5.10<\/b><\/span><\/span>-6<\/b><\/span><\/span><\/sup>\u00a0\u2013 0).0,6.10<\/b><\/span><\/span>-4<\/b><\/span><\/span><\/sup>\/2.10<\/b><\/span><\/span>-3<\/b><\/span><\/span><\/sup>\u00a0 —\u00a0 \u03b5= -1,5.10<\/b><\/span><\/span>-7<\/b><\/span><\/span><\/sup>V\u00a0 —\u00a0 em m\u00f3dulo\u00a0 —\u00a0\u00a0<\/b><\/span><\/span>\u03b5=1,5.10<\/b><\/span><\/span>-7<\/b><\/span><\/span><\/sup>V<\/b><\/span><\/span><\/p>\n

31-<\/b><\/span><\/span><\/span> <\/b>R- A<\/b><\/span><\/span>\u00a0 —\u00a0 veja teoria<\/b><\/span><\/span><\/p>\n

32-<\/b><\/span><\/span><\/span> <\/b>R- C\u00a0<\/b><\/span><\/span>\u00a0—\u00a0 veja teoria<\/b><\/span><\/span><\/p>\n

33-<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/span>R- E\u00a0 —\u00a0 veja teoria<\/b><\/span><\/span><\/p>\n

34-<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/span>Um transformador s\u00f3 funciona com corrente alternada\u00a0 —\u00a0<\/b><\/span><\/span>\u00a0R- C<\/b><\/span><\/span><\/p>\n

35-<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/span>\u201cas tens\u00f5es (voltagens) U<\/b><\/span><\/span>1<\/b><\/span><\/span><\/sub>\u00a0e U<\/b><\/span><\/span>2<\/b><\/span><\/span><\/sub>\u00a0s\u00e3o diretamente proporcionais ao n\u00famero de espiras N<\/b><\/span><\/span>1<\/b><\/span><\/span><\/sub>e N<\/b><\/span><\/span>2<\/b><\/span><\/span><\/sub>\u201d<\/b><\/span><\/span><\/p>\n

\"\"<\/p>\n

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

36-<\/b><\/span><\/span><\/span> <\/b>R- E<\/b><\/span><\/span>\u00a0 —\u00a0 veja teoria<\/b><\/span><\/span><\/p>\n

37-<\/b><\/span><\/span><\/span> <\/b>R- B<\/b><\/span><\/span>\u00a0 —\u00a0 veja teoria<\/b><\/span><\/span><\/p>\n

38-<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/span>01. A pot\u00eancia do prim\u00e1rio \u00e9 sempre igual \u00e0 do secund\u00e1rio (princ\u00edpio da conserva\u00e7\u00e3o da energia)\u00a0 —\u00a0 Correta<\/b><\/span><\/span><\/p>\n

02. Falsa\u00a0 —\u00a0 a bateria fornece corrente cont\u00ednua e, sem corrente alternada n\u00e3o haver\u00e1 fem induzida.<\/b><\/span><\/span><\/p>\n

04. Correta\u00a0 —\u00a0 veja 01<\/b><\/span><\/span><\/p>\n

08. As correntes s\u00e3o inversamente proporcionais \u00e0s tens\u00f5es\u00a0 —\u00a0 Falsa<\/b><\/span><\/span><\/p>\n

16. Este fen\u00f4meno \u00e9 devido \u00e0 indu\u00e7\u00e3o eletromagn\u00e9tica\u00a0 —\u00a0 Falsa<\/b><\/span><\/span><\/p>\n

R- (01 + 04) = 05<\/b><\/span><\/span><\/p>\n

39-<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/span>Como o gerador (bateria) s\u00f3 produz corrente cont\u00ednua, s\u00f3 haver\u00e1 deflex\u00e3o do ponteiro do galvan\u00f4metro quando houver varia\u00e7\u00e3o de corrente o que ocorre quando a chave \u00e9 ligada (aumento de corrente) ou desligada (diminui\u00e7\u00e3o de corrente)\u00a0 —<\/b><\/span><\/span>\u00a0 R- B<\/b><\/span><\/span><\/p>\n

40-<\/b><\/span><\/span><\/span> <\/b>R- Soma (02 + 04) = 06\u00a0 —\u00a0\u00a0<\/b><\/span><\/span>veja teoria<\/b><\/span><\/span><\/p>\n

41-<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

42-<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/span>a) 8.800\/220=N<\/b><\/span><\/span>1<\/b><\/span><\/span><\/sub>\/N<\/b><\/span><\/span>2<\/b><\/span><\/span><\/sub>\u00a0 —<\/b><\/span><\/span>\u00a0 N<\/b><\/span><\/span>1<\/b><\/span><\/span><\/sub>\/N<\/b><\/span><\/span>2<\/b><\/span><\/span><\/sub>=40<\/b><\/span><\/span><\/p>\n

b) A pot\u00eancia \u00e9 a mesma no prim\u00e1rio e no secund\u00e1rio\u00a0 —\u00a0 c\u00e1lculo da pot\u00eancia no secund\u00e1rio 2\u00a0 —\u00a0 P<\/b><\/span><\/span>s2<\/b><\/span><\/span><\/sub>=U<\/b><\/span><\/span>s2<\/b><\/span><\/span><\/sub>.i<\/b><\/span><\/span>s2<\/b><\/span><\/span><\/sub>\u00a0 —\u00a0 P<\/b><\/span><\/span>s2<\/b><\/span><\/span><\/sub>=220.150\u00a0 —\u00a0 P<\/b><\/span><\/span>s2<\/b><\/span><\/span><\/sub>=33.000W\u00a0 —\u00a0 a pot\u00eancia total no prim\u00e1rio \u00e9 a soma das pot\u00eancias nos dois secund\u00e1rios\u00a0 —\u00a0 P<\/b><\/span><\/span>1<\/b><\/span><\/span><\/sub>=P<\/b><\/span><\/span>s2<\/b><\/span><\/span><\/sub>\u00a0+ P<\/b><\/span><\/span>s1<\/b><\/span><\/span><\/sub>\u00a0 —\u00a0 81.000=33.000 + P<\/b><\/span><\/span>s1<\/b><\/span><\/span><\/sub>\u00a0 —\u00a0 P<\/b><\/span><\/span>s2<\/b><\/span><\/span><\/sub>=48.000W\u00a0 —\u00a0 P<\/b><\/span><\/span>s1\u00ad<\/b><\/span><\/span><\/sub>=U<\/b><\/span><\/span>s1<\/b><\/span><\/span><\/sub>.i<\/b><\/span><\/span>s1<\/b><\/span><\/span><\/sub>\u00a0 —\u00a0 48.000=120.i<\/b><\/span><\/span>s1<\/b><\/span><\/span><\/sub>\u00a0 —\u00a0<\/b><\/span><\/span>\u00a0i<\/b><\/span><\/span>s1<\/b><\/span><\/span><\/sub>=400A<\/b><\/span><\/span><\/p>\n

43-<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/span>i<\/b><\/span><\/span>1<\/b><\/span><\/span><\/sub>=2 A\u00a0 —\u00a0 U<\/b><\/span><\/span>1<\/b><\/span><\/span><\/sub>=80V\u00a0 —\u00a0 i<\/b><\/span><\/span>2<\/b><\/span><\/span><\/sub>=40 A\u00a0 —\u00a0 U<\/b><\/span><\/span>1<\/b><\/span><\/span><\/sub>\/U<\/b><\/span><\/span>2<\/b><\/span><\/span><\/sub>=i<\/b><\/span><\/span>2<\/b><\/span><\/span><\/sub>\/i<\/b><\/span><\/span>1<\/b><\/span><\/span><\/sub>\u00a0 —\u00a0 80\/U<\/b><\/span><\/span>2<\/b><\/span><\/span><\/sub>=40\/2\u00a0 —\u00a0 U<\/b><\/span><\/span>2<\/b><\/span><\/span><\/sub>=4,0V\u00a0 —\u00a0 U<\/b><\/span><\/span>1<\/b><\/span><\/span><\/sub>\/U<\/b><\/span><\/span>2<\/b><\/span><\/span><\/sub>=N<\/b><\/span><\/span>1<\/b><\/span><\/span><\/sub>\/N<\/b><\/span><\/span>2<\/b><\/span><\/span><\/sub>\u00a0 —\u00a0 80\/4=N<\/b><\/span><\/span>1<\/b><\/span><\/span><\/sub>\/N<\/b><\/span><\/span>2<\/b><\/span><\/span><\/sub>\u00a0 —\u00a0 N<\/b><\/span><\/span>1<\/b><\/span><\/span><\/sub>\/N<\/b><\/span><\/span>2<\/b><\/span><\/span><\/sub>=20\u00a0 —\u00a0\u00a0<\/b><\/span><\/span>R- D<\/b><\/span><\/span><\/p>\n

44-<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/span>01) Falsa\u00a0 —\u00a0 a intensidade da for\u00e7a eletromotriz induzida \u00e9 diretamente proporcional ao m\u00f3dulo da varia\u00e7\u00e3o do fluxo magn\u00e9tico<\/b><\/span><\/span><\/p>\n

\"\"<\/p>\n

em fun\u00e7\u00e3o do tempo, conforme a lei de Neumann-Faraday:.<\/b><\/span><\/span><\/p>\n

02) Correta\u00a0 —\u00a0 a lei de Lenz afirma que sempre que h\u00e1 varia\u00e7\u00e3o do fluxo magn\u00e9tico, surge uma for\u00e7a magn\u00e9tica na tend\u00eancia de anular o movimento que deu origem a essa varia\u00e7\u00e3o do fluxo.
\n04) Correta\u00a0 —\u00a0 dados: n = 50 espiras\u00a0 —\u00a0 i = 2 A\u00a0 —\u00a0 P = 5 W\u00a0 —\u00a0 P = U i\u00a0 —\u00a0 P = n.i.U\u00a0 —\u00a0 5 = 50. 2.U\u00a0 —\u00a0 U=0,05 V.
\n16) Correta\u00a0 —\u00a0 com o circuito aberto, n\u00e3o h\u00e1 condu\u00e7\u00e3o.
\n32) Falsa\u00a0 —\u00a0 parte desse trabalho \u00e9 dissipado na forma de calor na bobina e na l\u00e2mpada.\u00a0<\/b><\/span><\/span><\/p>\n

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

45-<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/span>a) Dados\u00a0 —\u00a0 U<\/b><\/span><\/span>1<\/b><\/span><\/span><\/sub>\u00a0= 110 V\u00a0 —\u00a0 U<\/b><\/span><\/span>2<\/b><\/span><\/span><\/sub>\u00a0= 220 V\u00a0 —\u00a0 N<\/b><\/span><\/span>1<\/b><\/span><\/span><\/sub>\u00a0= 250 espiras\u00a0 —\u00a0 sendo N<\/b><\/span><\/span>2<\/b><\/span><\/span><\/sub>\u00a0o n\u00famero de espiras<\/b><\/span><\/span><\/p>\n

correspondente a 220 V\u00a0 —\u00a0\u00a0 equa\u00e7\u00e3o do transformador\u00a0 —\u00a0 U<\/b><\/span><\/span>1<\/b><\/span><\/span><\/sub>\/N<\/b><\/span><\/span>1<\/b><\/span><\/span><\/sub>=U<\/b><\/span><\/span>2<\/b><\/span><\/span><\/sub>\/N<\/b><\/span><\/span>2<\/b><\/span><\/span><\/sub>\u00a0 —\u00a0 110\/250=220\/N<\/b><\/span><\/span>2<\/b><\/span><\/span><\/sub>\u00a0 —\u00a0\u00a0<\/b><\/span><\/span>N<\/b><\/span><\/span>2<\/b><\/span><\/span><\/sub>=500 espiras<\/b><\/span><\/span>\"\"<\/p>\n

b) P = 880 W\u00a0 —\u00a0 P=U<\/b><\/span><\/span><\/span>2<\/b><\/span><\/span><\/span><\/sub>i<\/b><\/span><\/span><\/span>2<\/b><\/span><\/span><\/span><\/sub>\u00a0 —\u00a0 880=220.i<\/b><\/span><\/span><\/span>2<\/b><\/span><\/span><\/span><\/sub>\u00a0 —\u00a0<\/b><\/span><\/span><\/span>\u00a0i<\/b><\/span><\/span><\/span>2<\/b><\/span><\/span><\/span><\/sub>=4 A<\/b><\/span><\/span><\/span>\u00a0 —\u00a0 P=U<\/b><\/span><\/span><\/span>1<\/b><\/span><\/span><\/span><\/sub>.i<\/b><\/span><\/span><\/span>1<\/b><\/span><\/span><\/span><\/sub>\u00a0 —\u00a0 880=110.i<\/b><\/span><\/span><\/span>1<\/b><\/span><\/span><\/span><\/sub>\u00a0 —<\/b><\/span><\/span><\/span>\u00a0i<\/b><\/span><\/span><\/span>1<\/b><\/span><\/span><\/span><\/sub>=8 A<\/b><\/span><\/span><\/span><\/p>\n

c) P<\/b><\/span><\/span>m\u00e1x<\/b><\/span><\/span><\/sub>=2.200 W\u00a0 —\u00a0 P<\/b><\/span><\/span>m\u00e1x<\/b><\/span><\/span><\/sub>=U<\/b><\/span><\/span>2<\/b><\/span><\/span><\/sub>.i<\/b><\/span><\/span>2m\u00e1x<\/b><\/span><\/span><\/sub>\u00a0 —\u00a0 2.200=220.i<\/b><\/span><\/span>2m\u00e1x<\/b><\/span><\/span><\/sub>\u00a0 —\u00a0\u00a0<\/b><\/span><\/span>i<\/b><\/span><\/span>2m\u00e1x<\/b><\/span><\/span><\/sub>=10 A\u00a0\u00a0<\/b><\/span><\/span>—\u00a0 P<\/b><\/span><\/span>m\u00e1x<\/b><\/span><\/span><\/sub>=U<\/b><\/span><\/span>1<\/b><\/span><\/span><\/sub>.i<\/b><\/span><\/span>1m\u00e1x<\/b><\/span><\/span><\/sub>\u00a0 —\u00a0 2.200=110.i<\/b><\/span><\/span>1m\u00e1x<\/b><\/span><\/span><\/sub>\u00a0 —\u00a0\u00a0<\/b><\/span><\/span>i<\/b><\/span><\/span>1m\u00e1x<\/b><\/span><\/span><\/sub>=20 A<\/b><\/span><\/span><\/p>\n

46-<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/span>Nas usinas hidrel\u00e9tricas, s\u00f3 haver\u00e1 corrente el\u00e9trica induzida se houver varia\u00e7\u00e3o de fluxo<\/b><\/span><\/span><\/p>\n

magn\u00e9tico o que s\u00f3 \u00e9 poss\u00edvel girando a espira e, assim,\u00a0 a corrente el\u00e9trica produzida \u00e9 alternada e, \u00e9 esse tipo de corrente que o transformador recebe\u00a0 —\u00a0 essa corrente el\u00e9trica induzida \u00e9 uma fun\u00e7\u00e3o senoidal do tempo e \u00e9 alternada porque ela percorre a espira ou bobina invertendo seu sentido durante um ciclo, como indica o gr\u00e1fico i X t.<\/b><\/span><\/span>\"\"<\/p>\n

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

47-<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/span>I. Correta\u00a0 —\u00a0 descoberta revolucion\u00e1ria no campo da F\u00edsica, ocorrida em 1831.<\/b><\/span><\/span><\/p>\n

II. Correta\u00a0 —\u00a0 sempre que h\u00e1 varia\u00e7\u00e3o do fluxo magn\u00e9tico, surge for\u00e7a eletromagn\u00e9tica no sentido de anular a varia\u00e7\u00e3o desse fluxo\u00a0 —\u00a0 surge tamb\u00e9m a for\u00e7a eletromotriz induzida (f.e.m)<\/b><\/span><\/span><\/p>\n

III. Correta\u00a0 —\u00a0 a for\u00e7a eletromotriz induzida provoca a apari\u00e7\u00e3o de uma corrente el\u00e9trica induzida.\u00a0<\/b><\/span><\/span><\/p>\n

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

48-<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/span>B=0,5W<\/b><\/span><\/span>b<\/b><\/span><\/span><\/sub>\/m<\/b><\/span><\/span>2<\/b><\/span><\/span><\/sup>=T\u00a0 —\u00a0 \u0444=B.S.cos\u03b1\u00a0 — \u00a0\u0444<\/b><\/span><\/span>inicial<\/b><\/span><\/span><\/sub>=B.S.cos0<\/b><\/span><\/span>o<\/b><\/span><\/span><\/sup>\u00a0=0,5.(0,1×0,1).1\u00a0 —\u00a0 \u0444<\/b><\/span><\/span>inicial<\/b><\/span><\/span><\/sub>=0,005W<\/b><\/span><\/span>b<\/b><\/span><\/span><\/sub>\u00a0 —\u00a0 \u0444<\/b><\/span><\/span>final<\/b><\/span><\/span><\/sub>=B.S.cos180<\/b><\/span><\/span>o<\/b><\/span><\/span><\/sup>= =0,5.(0,1×0,1).(-1)\u00a0 —\u00a0 \u0444<\/b><\/span><\/span>finall<\/b><\/span><\/span><\/sub>= – 0,005W\u00a0 —\u00a0 \u2206\u0444=- 0,005 – ,005= – 0,01W<\/b><\/span><\/span>b<\/b><\/span><\/span><\/sub>\u00a0 —\u00a0 em m\u00f3dulo\u00a0 —\u00a0 \u03b5=\u2206\u0444\/\u2206t\u00a0 —\u00a0 5=0,01\/\u2206t\u00a0 —\u00a0<\/b><\/span><\/span><\/p>\n

\u2206t=0,01\/5=1×10<\/b><\/span><\/span>-2<\/b><\/span><\/span><\/sup>\/5=0,2.10<\/b><\/span><\/span>-2<\/b><\/span><\/span><\/sup>\u00a0 —\u00a0 \u2206t=2,0.10<\/b><\/span><\/span>-3<\/b><\/span><\/span><\/sup>s\u00a0 —\u00a0<\/b><\/span><\/span>\u00a0R- C<\/b><\/span><\/span><\/p>\n

49-<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/span>Num transformador ideal, a rela\u00e7\u00e3o entre tens\u00f5es (V) e correntes (i) \u00e9 dada pela conserva\u00e7\u00e3o da energia\u00a0 —\u00a0 a pot\u00eancia no prim\u00e1rio \u00e9 igual \u00e0 pot\u00eancia no secund\u00e1rio\u00a0 —\u00a0 P<\/b><\/span><\/span>1<\/b><\/span><\/span><\/sub>= P<\/b><\/span><\/span>2<\/b><\/span><\/span><\/sub>\u00a0 —\u00a0 V<\/b><\/span><\/span>1<\/b><\/span><\/span><\/sub>. i<\/b><\/span><\/span>1<\/b><\/span><\/span><\/sub>\u00a0= V<\/b><\/span><\/span>2<\/b><\/span><\/span><\/sub>. i<\/b><\/span><\/span>2<\/b><\/span><\/span><\/sub>\u00a0 — se V<\/b><\/span><\/span>1<\/b><\/span><\/span><\/sub>\u00a0> V<\/b><\/span><\/span>2<\/b><\/span><\/span><\/sub>\u00a0 —\u00a0 i<\/b><\/span><\/span>1<\/b><\/span><\/span><\/sub>\u00a0< i<\/b><\/span><\/span>2<\/b><\/span><\/span><\/sub>\u00a0 —\u00a0 rela\u00e7\u00e3o entre as tens\u00f5es (V) e os n\u00fameros de espiras (N)\u00a0 —\u00a0 V<\/b><\/span><\/span>1<\/b><\/span><\/span><\/sub>\/N<\/b><\/span><\/span>1<\/b><\/span><\/span><\/sub>=V<\/b><\/span><\/span>2<\/b><\/span><\/span><\/sub>\/N<\/b><\/span><\/span>2<\/b><\/span><\/span><\/sub>\u00a0 —\u00a0 se V<\/b><\/span><\/span>1<\/b><\/span><\/span><\/sub>\u00a0> V<\/b><\/span><\/span>2<\/b><\/span><\/span><\/sub>\u00a0 —\u00a0 N<\/b><\/span><\/span>1<\/b><\/span><\/span><\/sub>\u00a0> N<\/b><\/span><\/span>2<\/b><\/span><\/span><\/sub>\u00a0 —\u00a0\u00a0<\/b><\/span><\/span>R- C<\/b><\/span><\/span><\/p>\n

50-<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/span>Existem tr\u00eas maneiras de aumentar a intensidade do campo magn\u00e9tico em uma\u00a0<\/b><\/span><\/span>bobina<\/b><\/span><\/span>, tamb\u00e9m conhecida por\u00a0<\/b><\/span><\/span>solen\u00f3ide<\/b><\/span><\/span>\u00a0\u00a0—\u00a0\u00a0aumentando o n\u00famero de espiras\u00a0 —\u00a0 \u00a0aumentando a intensidade de corrente el\u00e9trica e\u00a0 —\u00a0inserindo um material ferromagn\u00e9tico no interior das espiras\u00a0 —\u00a0 a\u00a0intensidade da corrente induzida depende da varia\u00e7\u00e3o do fluxo magn\u00e9tico gerado pela corrente na bobina\u00a0 —\u00a0\u00a0 quanto mais intensa for a corrente na bobina, maior ser\u00e1 a intensidade da corrente induzida no c\u00e9rebro.\u00a0<\/b><\/span><\/span>\"\"<\/p>\n

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

51-<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/span>T=5.10<\/b><\/span><\/span>-2<\/b><\/span><\/span><\/sup>\u00a0s\u00a0 —\u00a0 velocidade angular w\u00a0 —\u00a0 w=2\u03c0f=2.\u03c0.20\u00a0 —\u00a0 w=40\u03c0 rad\/s\u00a0 —\u00a0 substituindo esses<\/b><\/span><\/span><\/p>\n

valores na fun\u00e7\u00e3o dada\u00a0 — \u0444 = B.S.coswt = 2.10<\/b><\/span><\/span>-5<\/b><\/span><\/span><\/sup>.10<\/b><\/span><\/span>-3<\/b><\/span><\/span><\/sup>.cos 40<\/b><\/span><\/span>\u03c0<\/b><\/span><\/span><\/span>t\u00a0 —\u00a0 \u0444 = 2.10<\/b><\/span><\/span>-8.<\/b><\/span><\/span><\/sup>cos 40\u03c0t\u00a0 —\u00a0 quando t = 0, o fluxo \u00e9 m\u00e1ximo e vale\u00a0 — \u0444<\/b><\/span><\/span>m\u00e1ximo<\/b><\/span><\/span><\/sub>=2.10<\/b><\/span><\/span>-8<\/b><\/span><\/span><\/sup>.cos0<\/b><\/span><\/span>o<\/b><\/span><\/span><\/sup>\u00a0 — \u0444<\/b><\/span><\/span>m\u00e1ximo<\/b><\/span><\/span><\/sub>=2.10<\/b><\/span><\/span>-8<\/b><\/span><\/span><\/sup>Wb\u00a0 —\u00a0 quando t=T\/2, a espira efetuou meia volta e o fluxo atrav\u00e9s dela \u00e9 m\u00ednimo e de valor\u00a0 —\u00a0 \u0444<\/b><\/span><\/span>m\u00ednimo<\/b><\/span><\/span><\/sub>= 2.10<\/b><\/span><\/span>-2<\/b><\/span><\/span><\/sup>.cos 40\u03c0.5.10<\/b><\/span><\/span>-2<\/b><\/span><\/span><\/sup>\/2 = 2.10<\/b><\/span><\/span>-2<\/b><\/span><\/span><\/sup>.cos\u03c0=2.10<\/b><\/span><\/span>-8<\/b><\/span><\/span><\/sup>.(-1) —\u00a0 \u0444<\/b><\/span><\/span>m\u00ednimo<\/b><\/span><\/span><\/sub>\u00a0= – 2.10<\/b><\/span><\/span>-8<\/b><\/span><\/span><\/sup>\u00a0Wb\u00a0 —\u00a0 observe ao lado o gr\u00e1fico pedido:<\/b><\/span><\/span>\"\"<\/p>\n

52-<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/span>Dados\u00a0 —\u00a0 N = 10 espiras\u00a0 — \u00a0D = 10 cm = 10<\/b><\/span><\/span>-1<\/b><\/span><\/span><\/sup>\u00a0m\u00a0 —\u00a0 B = 10<\/b><\/span><\/span>-2<\/b><\/span><\/span><\/sup>\u00a0T\u00a0 —\u00a0 f = 2 Hz\u00a0 —\u00a0 express\u00e3o do fluxo magn\u00e9tico\u00a0 —\u00a0 \u0444=N.B.S.cos\u03b1\u00a0 —\u00a0 N –\u00a0 n\u00famero de espiras\u00a0 —\u00a0 S – \u00e1rea de fluxo atrav\u00e9s da espira\u00a0 — B – intensidade do vetor indu\u00e7\u00e3o magn\u00e9tica\u00a0 —\u00a0 \u03b1 – \u00e2ngulo formado entre as linhas de indu\u00e7\u00e3o magn\u00e9tica (\"\") e a normal (\"\") ao plano da espira\u00a0 —\u00a0 observe que, para a situa\u00e7\u00e3o inicial,\u00a0\"\"\u00a0e<\/b><\/span><\/span><\/p>\n

\"\"<\/p>\n

\u00a0\"\"\u00a0s\u00e3o paralelos, ou seja, \u03b1=0<\/b><\/span><\/span>o<\/b><\/span><\/span><\/sup>\u00a0 —\u00a0 \u0444<\/b><\/span><\/span>inicialL<\/b><\/span><\/span><\/sub>= N.B.S.cos\u03b1=N.B.\u03c0R<\/b><\/span><\/span>2<\/b><\/span><\/span><\/sup>.cos0<\/b><\/span><\/span>o<\/b><\/span><\/span><\/sup>\u00a0 —\u00a0 \u0444<\/b><\/span><\/span>inicial<\/b><\/span><\/span><\/sub>=10.(10<\/b><\/span><\/span>-2<\/b><\/span><\/span><\/sup>).\u03c0.(D<\/b><\/span><\/span>2<\/b><\/span><\/span><\/sup>\/4).1=10<\/b><\/span><\/span>-1<\/b><\/span><\/span><\/sup>.(\u03c0.10<\/b><\/span><\/span>-2<\/b><\/span><\/span><\/sup>)\/4\u00a0 —\u00a0<\/b><\/span><\/span><\/p>\n

\u0424<\/b><\/span><\/span>inicial<\/b><\/span><\/span><\/sub>=2,5.\u03c0.10<\/b><\/span><\/span>-4<\/b><\/span><\/span><\/sup>\u00a0Wb\u00a0 — observe que, para a situa\u00e7\u00e3o final, depois de um giro de 90<\/b><\/span><\/span>o<\/b><\/span><\/span><\/sup>,\u00a0\"\"\u00a0e\u00a0\"\"\u00a0s\u00e3o perpendiculares, ou seja, \u03b1=90<\/b><\/span><\/span>o<\/b><\/span><\/span><\/sup>\u00a0 —\u00a0\u00a0 \u0444<\/b><\/span><\/span>final<\/b><\/span><\/span><\/sub>=N.B.S.cos90<\/b><\/span><\/span>o<\/b><\/span><\/span><\/sup>\u00a0 —\u00a0 \u0444<\/b><\/span><\/span>final<\/b><\/span><\/span><\/sub>=0\u00a0 —\u00a0 o tempo decorrido entre as situa\u00e7\u00f5es final e inicial \u00e9 de 1\/4de rota\u00e7\u00e3o ou de 1\/4 do per\u00edodo T\u00a0 —\u00a0 \u2206t=T\/4\u00a0 —\u00a0 T=1\/f=1\/2\u00a0 —\u00a0 \u2206t=(1\/2)\/4\u00a0 —\u00a0 \u2206t=1\/8 s\u00a0 — \u00a0lei de Faraday-Neumann\u00a0 —\u00a0 \u03b5= – \u2206\u0444\/\u2206\u00a0 —\u00a0 \u03b5 =\u00a0 – (0 -2,5\u03c0.10<\/b><\/span><\/span>-4<\/b><\/span><\/span><\/sup>)\/(1\/8)\u00a0 —\u00a0<\/b><\/span><\/span>\u00a0\u03b5\u2248 6,3.10<\/b><\/span><\/span>-3<\/b><\/span><\/span><\/sup>\u00a0V<\/b><\/span><\/span><\/p>\n

53-<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/span>01. Falsa\u00a0 —\u00a0 depende tamb\u00e9m da intensidade da corrente el\u00e9trica que percorre a espira e dos raios das espiras.<\/b><\/span><\/span><\/p>\n

02. Falsa\u00a0 —\u00a0 quando a corrente i circula pelos fios da bobina, produz nela um campo magn\u00e9tico vari\u00e1vel invertendo periodicamente sua polaridade\u00a0 —\u00a0 mas, estando a bobina imersa no campo magn\u00e9tico uniforme de um im\u00e3, ela passa a vibrar, fazendo vibrar tamb\u00e9m o cone\u00a0 —\u00a0 observe que n\u00e3o ocorre indu\u00e7\u00e3o eletromagn\u00e9tica.<\/b><\/span><\/span><\/p>\n

04. Falsa\u00a0 —\u00a0 a vibra\u00e7\u00e3o do cone produz no ar ondas longitudinais onde a dire\u00e7\u00e3o de propaga\u00e7\u00e3o coincide com a dire\u00e7\u00e3o de vibra\u00e7\u00e3o das part\u00edculas do ar.<\/b><\/span><\/span><\/p>\n

08. Correta\u00a0 —\u00a0 a altura do som est\u00e1 relacionada com a frequ\u00eancia (som agudo, frequ\u00eancia mais alta, som grave, frequ\u00eancia mais baixa).<\/b><\/span><\/span><\/p>\n

16- Correta\u00a0 —\u00a0 quanto maior a intensidade da corrente el\u00e9trica na bobina, mais intenso ser\u00e1 o campo magn\u00e9tico por ela gerado e, consequentemente, maiores ser\u00e3o as for\u00e7as de atra\u00e7\u00e3o e de repuls\u00e3o trocadas entre o im\u00e3 e a bobina\u00a0 —\u00a0 isso aumenta a amplitude do movimento vibrat\u00f3rio, aumentando tamb\u00e9m sua intensidade.<\/b><\/span><\/span><\/p>\n

32- Correta\u00a0 —\u00a0 veja justificativa anterior<\/b><\/span><\/span><\/p>\n

R- (08 + 16 + 32)= 56<\/b><\/span><\/span><\/p>\n

 <\/p>\n

54-<\/b><\/span><\/span><\/span><\/p>\n

Observe atentamente as express\u00f5es abaixo:<\/b><\/span><\/span><\/p>\n

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

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

 <\/p>\n

01- Falsa\u00a0 —\u00a0 a for\u00e7a eletromotriz induzida \u03b5 \u00e9 nula, pois B \u00e9 constante e o fluxo magn\u00e9tico \u03a6 n\u00e3o sofre varia\u00e7\u00e3o.<\/b><\/span><\/span><\/p>\n

02. Falsa\u00a0 —\u00a0 \u00e1rea da espira\u00a0 —\u00a0 S=\u03c0.r<\/b><\/span><\/span>2<\/b><\/span><\/span><\/sup>=\u03c0.(0,4\/\u221a\u03c0)<\/b><\/span><\/span>2<\/b><\/span><\/span><\/sup>\u00a0 —\u00a0 S=0,16m<\/b><\/span><\/span>2<\/b><\/span><\/span><\/sup>\u00a0 —\u00a0 t=0\u00a0 —\u00a0 \u03a6=0\u00a0 —\u00a0 t=1s\u00a0 —\u00a0 \u03a6=1.0,16=0,16T\u00a0 —<\/b><\/span><\/span><\/p>\n

\u2206\u03a6=0,16 \u2013 0=0,16Wb\u00a0 —\u00a0 \u03b5=-\u2206\u03a6\/\u2206t=0,16\/1= – 0,16V.<\/b><\/span><\/span><\/p>\n

04. Falsa\u00a0 — \u03b5 vale + 0,16V (veja 02)<\/b><\/span><\/span><\/p>\n

08. Correta\u00a0 —\u00a0 entre t=5s e t=6s, \u03b5=0,16V (veja 04)\u00a0 —\u00a0 R= \u03b5\/i\u00a0 —\u00a0 8=0,16\/i\u00a0 —\u00a0 i=0,02 A.<\/b><\/span><\/span><\/p>\n

16. Correta\u00a0 —\u00a0 \u03a6=B.S e, como S \u00e9 constante a varia\u00e7\u00e3o de B \u00e9 proporcional \u00e0 varia\u00e7\u00e3o de \u03a6.<\/b><\/span><\/span><\/p>\n

32. Falsa\u00a0 —\u00a0 a for\u00e7a eletromotriz \u00e9 calculada com base na lei de Lenz.<\/b><\/span><\/span><\/p>\n

Corretas: 08 e 16\u00a0 —\u00a0<\/b><\/span><\/span>\u00a0Soma=24<\/b><\/span><\/span>.<\/b><\/span><\/span><\/p>\n

 <\/p>\n

55-<\/b><\/span><\/span><\/span> A intensidade da for\u00e7a magn\u00e9tica (\"\") sobre o fio vale\u00a0 —\u00a0\u00a0 F<\/b><\/span><\/span>m<\/b><\/span><\/span><\/sub>=B.i.L.sen90<\/b><\/span><\/span>o<\/b><\/span><\/span><\/sup>\u00a0=B.i.L.1=B.i.L=B.i\u00a0 —\u00a0 a parcela da f for\u00e7a peso respons\u00e1vel pela descida do fio no plano inclinado de 30<\/b><\/span><\/span>o<\/b><\/span><\/span><\/sup>\u00a0vale\u00a0 —\u00a0 P<\/b><\/span><\/span>p<\/b><\/span><\/span><\/sub>=m.g.sen30<\/b><\/span><\/span>o<\/b><\/span><\/span><\/sup>=5.10.1\/2=25N\u00a0 —\u00a0 quando o fio se move com velocidade constante ele est\u00e1 em equil\u00edbrio din\u00e2mico e a for\u00e7a resultante sobre ele \u00e9 nula (\"\") e, para que isso ocorra F<\/b><\/span><\/span>m<\/b><\/span><\/span><\/sub>=P<\/b><\/span><\/span>p<\/b><\/span><\/span><\/sub>\u00a0 —\u00a0 B.i=25\u00a0 —\u00a0 i=25\/B (I)\u00a0 —\u00a0 a for\u00e7a eletromotriz induzida \u03b5 \u00e9 fornecida por \u03b5=B.L.v\u00a0 —\u00a0 R=U\/i=\u03b5\/i\u00a0 —\u00a0 \u03b5=R.i\u00a0 —\u00a0 \u03b5=2.i\u00a0 —\u00a0 2.i=B.L.v\u00a0 —\u00a0 2i=B.1.2\u00a0 —\u00a0 i=B\u00a0 —\u00a0 substituindo em (I) \u00a0—\u00a0 B=25\/B\u00a0 —\u00a0 B<\/b><\/span><\/span>2<\/b><\/span><\/span><\/sup>=25\u00a0 —\u00a0 B=5 T\u00a0 —\u00a0\u00a0<\/b><\/span><\/span>R- C<\/b><\/span><\/span>.<\/b><\/span><\/span>\"\"<\/p>\n

56- <\/b><\/span><\/span><\/span>A tens\u00e3o Vrs\u00a0entre\u00a0 r e s da barra corresponde \u00e0 for\u00e7a eletromotriz induzida fornecida pela lei de Lenz\u00a0 —\u00a0 \u03b5=Vrs=|\u2206\u03a6|\/\u2206t\u00a0 —\u00a0 por essa express\u00e3o, quanto maior for a velocidade da barra rs, maior ser\u00e1 a varia\u00e7\u00e3o da \u00e1rea da espira, maior ser\u00e1 a varia\u00e7\u00e3o do fluxo magn\u00e9tico \u2206\u03a6 e consequentemente maior ser\u00e1 a tens\u00e3o Vrs\u00a0induzida\u00a0 —\u00a0 a velocidade de rs e a tens\u00e3o Vrs s\u00e3o maiores\u00a0 em (3) onde a velocidade \u00e9 m\u00e1xima e nulas em (1) e (4) onde a velocidade \u00e9 nula\u00a0 —\u00a0\u00a0R- C.<\/b><\/span><\/span><\/p>\n

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

A lei de Faraday-Neuman afirma que a for\u00e7a eletromotriz \u03b5 (tens\u00e3o, ddp) induzida, num mesmo intervalo de tempo \u2206t, \u00e9 tanto maior quanto maior for a varia\u00e7\u00e3o\u00a0(\u2206\u03a6)\u00a0do fluxo magn\u00e9tico de\u00a0\"\"\u00a0— \u00a0\u03b5=\u2206\u03a6\/\u2206t\u00a0 —\u00a0 a lei de Ohm fornece a intensidade de corrente el\u00e9trica que surge na espira de resist\u00eancia R com a varia\u00e7\u00e3o do fluxo do vetor campo magn\u00e9tico campo magn\u00e9tico\u00a0 —\u00a0 R=U\/i= \u03b5\/i\u00a0 — \u03b5=R.i\u00a0 —\u00a0 =\u2206Q\/\u2206t\u00a0 —\u00a0 \u2206Q=n.e\u00a0 —\u00a0 n \u2013 n\u00famero de el\u00e9trons\u00a0 —\u00a0 e \u2013 m\u00f3dulo da carga de um el\u00e9tron\u00a0 —\u00a0 i=n.e\/\u2206t\u00a0 —\u00a0 \u03b5=R.i=R. n.e\/\u2206t\u00a0 — \u2206\u03a6\/\u2206t = R. n.e\/\u2206t\u00a0\u00a0 —\u00a0 n= \u2206\u03a6\/R.e\u00a0 —\u00a0 observe que o n\u00famero de el\u00e9trons n independe de qualquer intervalo de tempo de oscila\u00e7\u00e3o do im\u00e3, inclusive se seu per\u00edodo T\u00a0 —\u00a0\u00a0R-\u00a0 D<\/b><\/span><\/span><\/p>\n

 <\/p>\n

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

Resolu\u00e7\u00e3o comentada dos exerc\u00edcios de vestibulares sobre For\u00e7a Eletromotriz Induzida \u2013 Transformadores 01– A corrente est\u00e1 sendo induzida (indu\u00e7\u00e3o eletromagn\u00e9tica) e muda de sentido no \u201cvai e vem\u201d do im\u00e3\u00a0 —\u00a0\u00a0R- A 02-\u00a0 Fluxo inicial\u00a0 —\u00a0 \u03a6o\u00a0=37.10-3Wb\u00a0 —\u00a0 fluxo final\u00a0 —\u00a0\u00a0\u00a0 \u03a6=0\u00a0 —\u00a0 varia\u00e7\u00e3o de fluxo\u00a0 —\u00a0 \u0394\u03a6=\u03a6 – \u03a6o=37.10-3\u00a0\u2013 0\u00a0 —\u00a0 \u0394\u03a6=37.10-3Wb\u00a0 —\u00a0 \u03b5=\u0394\u03a6\/\u0394t=37.10-3\/10-3\u00a0 —\u00a0\u00a0\u03b5=37V 03-\u00a001. Correta\u00a0 —\u00a0 quando<\/p>\n","protected":false},"author":1,"featured_media":0,"parent":1968,"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-1971","page","type-page","status-publish","hentry"],"aioseo_notices":[],"_links":{"self":[{"href":"https:\/\/fisicaevestibular.com.br\/novo\/wp-json\/wp\/v2\/pages\/1971","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=1971"}],"version-history":[{"count":4,"href":"https:\/\/fisicaevestibular.com.br\/novo\/wp-json\/wp\/v2\/pages\/1971\/revisions"}],"predecessor-version":[{"id":10577,"href":"https:\/\/fisicaevestibular.com.br\/novo\/wp-json\/wp\/v2\/pages\/1971\/revisions\/10577"}],"up":[{"embeddable":true,"href":"https:\/\/fisicaevestibular.com.br\/novo\/wp-json\/wp\/v2\/pages\/1968"}],"wp:attachment":[{"href":"https:\/\/fisicaevestibular.com.br\/novo\/wp-json\/wp\/v2\/media?parent=1971"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}