{"id":2221,"date":"2016-05-14T23:57:39","date_gmt":"2016-05-14T23:57:39","guid":{"rendered":"http:\/\/fisicaevestibular.com.br\/novo\/?page_id=2221"},"modified":"2024-09-02T14:19:37","modified_gmt":"2024-09-02T14:19:37","slug":"laminas-de-faces-paralelas-resolucao","status":"publish","type":"page","link":"https:\/\/fisicaevestibular.com.br\/novo\/optica\/optica-geometrica\/laminas-de-faces-paralelas\/laminas-de-faces-paralelas-resolucao\/","title":{"rendered":"L\u00e2minas de faces paralelas – Resolu\u00e7\u00e3o"},"content":{"rendered":"

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

L\u00e2minas de faces paralelas<\/b><\/span><\/span><\/span><\/p>\n

01-<\/b><\/span><\/span><\/span> <\/b>Lei de Snell-Descartes – A rela\u00e7\u00e3o entre o seno do \u00e2ngulo de incid\u00eancia e o seno do \u00e2ngulo de refra\u00e7\u00e3o \u00e9 uma grandeza constante denominada \u00edndice de refra\u00e7\u00e3o do segundo meio em rela\u00e7\u00e3o ao primeiro, ou seja,\u00a0 seni\/senr=n<\/b><\/span><\/span>2<\/b><\/span><\/span><\/sub>\/n<\/b><\/span><\/span>1<\/b><\/span><\/span><\/sub>\u00a0\u00a0\u00a0<\/b><\/span><\/span><\/p>\n

\"\"<\/p>\n

\"\"<\/p>\n

As express\u00f5es acima nos mostram que quando a luz passar de um meio menos refringente (menor indice de refra\u00e7\u00e3o) para um meio mais refringente (maior \u00edndice de refra\u00e7\u00e3o), o \u00e2ngulo de refra\u00e7\u00e3o ser\u00e1 menor que o \u00e2ngulo de incid\u00eancia (ele se aproxima da normal) e menor ser\u00e1 a velocidade da luz nele\u00a0 —\u00a0 no caso do exerc\u00edcio, veja na figura fornecida que \u03b8<\/b><\/span><\/span>1<\/b><\/span><\/span><\/sub>\u00a0> \u03b8<\/b><\/span><\/span>2<\/b><\/span><\/span><\/sub>, o que implica que n<\/b><\/span><\/span>B<\/b><\/span><\/span><\/sub>\u00a0> n<\/b><\/span><\/span>A<\/b><\/span><\/span><\/sub>\u00a0 —\u00a0 assim, V<\/b><\/span><\/span>A<\/b><\/span><\/span><\/sub>\u00a0> V<\/b><\/span><\/span>B<\/b><\/span><\/span><\/sub>\u00a0 —\u00a0<\/b><\/span><\/span>\u00a0R- A.<\/b><\/span><\/span><\/p>\n

 <\/p>\n

02-<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/span>Aplicando Snell-Descartes\u00a0 —\u00a0 n<\/b><\/span><\/span>ar<\/b><\/span><\/span><\/sub>.seni=n<\/b><\/span><\/span>l\u00e2mina<\/b><\/span><\/span><\/sub>.senr\u00a0 —\u00a0 1.\u221a2\/2=\u221a2.senr\u00a0 —\u00a0 senr=1\/2\u00a0 —\u00a0 r=30<\/b><\/span><\/span>o<\/b><\/span><\/span><\/sup>\u00a0 —\u00a0 aplicando a f\u00f3rmula do desvio latera\u00a0 —\u00a0 d=e.sen(i \u2013 r)\/cosr\u00a0 —\u00a0 d=1,4.sen(45 \u2013 30)\/cos30<\/b><\/span><\/span>o<\/b><\/span><\/span><\/sup>\u00a0 —\u00a0 d=0,364\/0,86\u00a0 —\u00a0\u00a0d=0,42cm.<\/b><\/span><\/span><\/p>\n

03-<\/b><\/span><\/span><\/span>\u00a0\u00a0<\/b><\/span><\/span><\/span>A imagem de um objeto vista atrav\u00e9s de uma l\u00e2mina de faces paralelas (placa de vidro no ar) \u00e9 sempre\u00a0virtual\u00a0e est\u00e1 sempre mais pr\u00f3xima da l\u00e2mina que o objeto, pois ao penetrarem na l\u00e2mina os raios de luz se aproximam da normal.<\/b><\/span><\/span><\/p>\n

\"\"<\/p>\n

 <\/p>\n

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

04-<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/span>Um observador que v\u00ea um peixe dentro de um aqu\u00e1rio enxerga-o mais pr\u00f3ximo da parede do aqu\u00e1rio\u00a0<\/b><\/span><\/span><\/p>\n

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

Ao mesmo tempo, o peixe v\u00ea o observador mais distante do aqu\u00e1rio.\u00a0 —\u00a0 R- A<\/b><\/span><\/span><\/p>\n

05-<\/b><\/span><\/span><\/span>\u00a0\u00a0 <\/b><\/span><\/span><\/span>R- D\u00a0 —\u00a0 os raios incidente e emergente s\u00e3o paralelos e, portanto, os \u00e2ngulos a e g s\u00e3o iguais.\u00a0\u00a0<\/b><\/span><\/span><\/p>\n

06-<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/span>Os \u00e2ngulos incidente e emergente s\u00e3o iguais porque os prolongamentos dos raios incidente e emergente s\u00e3o paralelos<\/b><\/span><\/span><\/p>\n

\"\"<\/p>\n

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

07-<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/span>Veja a figura abaixo:<\/b><\/span><\/span><\/p>\n

Se o raio de luz sofrer reflex\u00e3o e refra\u00e7\u00e3o em ambas as faces e, nelas, retornar ao ar, os seguintes \u00e2ngulos ser\u00e3o iguais:<\/b><\/span><\/span><\/p>\n

\"\"<\/p>\n

a=b=g=h\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 c=d=e=f\u00a0\u00a0 —\u00a0 R-\u00a0a=qi,\u00a0\u00a0b=q<\/b><\/span><\/span>r<\/b><\/span><\/span><\/sub>\u00a0\u00a0e\u00a0\u00a0l=qi\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/b><\/span><\/span><\/p>\n

08-<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/span>O desvio angular \u00e9\u00a0nulo, pois n\u00e3o h\u00e1 mudan\u00e7a de dire\u00e7\u00e3o dos raios incidentes e emergentes\u00a0\u00a0<\/b><\/span><\/span><\/p>\n

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

09-<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/span>Como o raio de luz incide perpendicularmente, ele n\u00e3o sofre desvio\u00a0 —\u00a0 c\u00e1lculo da velocidade do raio de luz no interior do vidro\u00a0<\/b><\/span><\/span><\/p>\n

\"\"<\/p>\n

N<\/b><\/span><\/span>vidro<\/b><\/span><\/span><\/sub>=C\/V<\/b><\/span><\/span>vidro<\/b><\/span><\/span><\/sub>\u00a0 —\u00a0 1,5=3.10<\/b><\/span><\/span>8<\/b><\/span><\/span><\/sup>\/V<\/b><\/span><\/span>vidro<\/b><\/span><\/span><\/sub>\u00a0 —\u00a0 V<\/b><\/span><\/span>vidro<\/b><\/span><\/span><\/sub>=2.10<\/b><\/span><\/span>8<\/b><\/span><\/span><\/sup>m\/s\u00a0 —\u00a0 para percorrer e=PQ com V=2.10<\/b><\/span><\/span>8<\/b><\/span><\/span><\/sup>m\/s, a luz demora t=10<\/b><\/span><\/span>-10<\/b><\/span><\/span><\/sup>s\u00a0 —\u00a0 V=e\/t\u00a0 —\u00a0 2.10<\/b><\/span><\/span>8<\/b><\/span><\/span><\/sup>=e\/10<\/b><\/span><\/span>-10<\/b><\/span><\/span><\/sup>\u00a0 —\u00a0\u00a0e=2.10<\/b><\/span><\/span>-2<\/b><\/span><\/span><\/sup>m=2,0cm<\/b><\/span><\/span><\/p>\n

10-<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/span>a)<\/b><\/span><\/span><\/p>\n

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

b)Aplicando Snell-Descartes na face superior\u00a0 —\u00a0 n(ar).seni=n(vidro).senr\u00a0 —\u00a0 1.0,9=1,5.senr\u00a0 —\u00a0 senr=0,6\u00a0 —\u00a0 sen<\/b><\/span><\/span>2<\/b><\/span><\/span><\/sup>r + cos<\/b><\/span><\/span>2<\/b><\/span><\/span><\/sup>r=1\u00a0 —<\/b><\/span><\/span><\/p>\n

\"\"<\/p>\n

–\u00a0 (0,6)<\/b><\/span><\/span>2<\/b><\/span><\/span><\/sup>+ cos<\/b><\/span><\/span>2<\/b><\/span><\/span><\/sup>r=1 —\u00a0 cosr=0,8\u00a0 —\u00a0\u00a0 cosr=cateto adjacente\/hipotenusa\u00a0 —\u00a0 0.8=0.08\/S\u00a0 —\u00a0 S==0,1m\u00a0 —\u00a0 c\u00e1lculo da velocidade da luz no vidro\u00a0 —\u00a0 n<\/b><\/span><\/span>vidro<\/b><\/span><\/span><\/sub>=C\/V<\/b><\/span><\/span>vidro<\/b><\/span><\/span><\/sub>\u00a0 —\u00a0 1,5=3.10<\/b><\/span><\/span>8<\/b><\/span><\/span><\/sup>\/V<\/b><\/span><\/span>vidro0,5.10<\/b><\/span><\/span><\/sub>-9<\/b><\/span><\/span><\/sup>\u00a0 —\u00a0 V<\/b><\/span><\/span>vidro<\/b><\/span><\/span><\/sub>=2,0.10<\/b><\/span><\/span>8<\/b><\/span><\/span><\/sup>m\/s\u00a0 —\u00a0 V<\/b><\/span><\/span>vidro<\/b><\/span><\/span><\/sub>=S\/t\u00a0 —\u00a0 2.10<\/b><\/span><\/span>8<\/b><\/span><\/span><\/sup>=10<\/b><\/span><\/span>-1<\/b><\/span><\/span><\/sup>\/t\u00a0 —\u00a0 t=10<\/b><\/span><\/span>-1<\/b><\/span><\/span><\/sup>\/2.10<\/b><\/span><\/span>8<\/b><\/span><\/span><\/sup>\u00a0 —<\/b><\/span><\/span><\/p>\n

t=5,0.10<\/b><\/span><\/span>-10<\/b><\/span><\/span><\/sup>s<\/b><\/span><\/span><\/p>\n

11-<\/b><\/span><\/span><\/span>\u00a0\u00a0<\/b><\/span><\/span><\/span>R- D \u2013 diferentes cores sofrem desvios diferentes e, consequentemente, deslocamentos paralelos diferentes<\/b><\/span><\/span><\/p>\n

12-<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/span>Veja figura abaixo:<\/b><\/span><\/span><\/p>\n

\"\"<\/p>\n

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

13-<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/span>Observe a figura abaixo:<\/b><\/span><\/span><\/p>\n

\"\"<\/p>\n

\u03b8=30<\/b><\/span><\/span>o<\/b><\/span><\/span><\/sup>\u00a0 —\u00a0 tg30<\/b><\/span><\/span>o<\/b><\/span><\/span><\/sup>=\u221a3\/3\u00a0 —\u00a0 tg30<\/b><\/span><\/span>o<\/b><\/span><\/span><\/sup>=cateto oposto\/cateto adjacente\u00a0 —\u00a0 \u221a3\/3=(1 + y)\/2\u221a3\u00a0 —\u00a0 y=1cm\u00a0 —\u00a0 se X=Y=1cm \u2013 2\u03b8=r\u00a0 —\u00a0 2.30<\/b><\/span><\/span>o<\/b><\/span><\/span><\/sup>=r\u00a0 —\u00a0 r=15<\/b><\/span><\/span>o<\/b><\/span><\/span><\/sup>\u00a0 — aplicando Snell-Descartes na face superior\u00a0 —\u00a0 n<\/b><\/span><\/span>1<\/b><\/span><\/span><\/sub>.sen30<\/b><\/span><\/span>o<\/b><\/span><\/span><\/sup>=n<\/b><\/span><\/span>2<\/b><\/span><\/span><\/sub>.sen15<\/b><\/span><\/span>o<\/b><\/span><\/span><\/sup>\u00a0 —\u00a0 1.0,5=n<\/b><\/span><\/span>2<\/b><\/span><\/span><\/sub>.0,26\u00a0 —\u00a0\u00a0n<\/b><\/span><\/span>2<\/b><\/span><\/span><\/sub>=1,9<\/b><\/span><\/span><\/p>\n

14-<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/span>Quando a luz se refrata de um meio de menor \u00edndice de refra\u00e7\u00e3o para outro de maior \u00edndice de refra\u00e7\u00e3o, o raio refratado se aproxima da normal\u00a0\u00a0—\u00a0 R- B<\/b><\/span><\/span><\/p>\n

15-<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/span>R- n<\/b><\/span><\/span>A<\/b><\/span><\/span><\/sub><\u00a0n<\/b><\/span><\/span>B\u00a0<\/b><\/span><\/span><\/sub>>\u00a0n<\/b><\/span><\/span>C \u00ad\u00a0<\/b><\/span><\/span><\/sub>– Veja justificativa da quest\u00e3o anterior<\/b><\/span><\/span>\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/b><\/span><\/span><\/sub><\/p>\n

16-<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/span>R- B\u00a0–\u00a0 —\u00a0 I vidro\/II \u00e1gua –\u00a0 sofre refra\u00e7\u00e3o quando passa do meio mais refringente para o menos refringente\u00a0 —\u00a0 II \u00e1gua\/III ar \u2013 sofre reflex\u00e3o total quando passa do meio mais refringente para o menos refringente.<\/b><\/span><\/span><\/p>\n

17-<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/span>Como a imagem est\u00e1 acima do observador, ela estar\u00e1 mais pr\u00f3xima do mesmo e, devido ao campo visual maior dar\u00e1 ao observador a impress\u00e3o de ser maior que o objeto\u00a0R- D\u00a0<\/b><\/span><\/span><\/p>\n

18-<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/span>(01) Falsa \u2013 eles possuem a mesma dire\u00e7\u00e3o, ou seja, s\u00e3o paralelos.<\/b><\/span><\/span><\/p>\n

(02) n<\/b><\/span><\/span>ar<\/b><\/span><\/span><\/sub>.sen60<\/b><\/span><\/span>o<\/b><\/span><\/span><\/sup>=n.senr\u00a0 —\u00a0 1.\u221a3\/2=\u221a3.senr\u00a0 —\u00a0 senr=1\/2\u00a0 —\u00a0 r=30<\/b><\/span><\/span>o<\/b><\/span><\/span><\/sup>\u00a0\u2013 correta.<\/b><\/span><\/span><\/p>\n

(04) d=e.sen(i \u2013 r)\/cosr\u00a0 —\u00a0 d=2\u221a3.sen(60<\/b><\/span><\/span>o<\/b><\/span><\/span><\/sup>\u00a0\u2013 30<\/b><\/span><\/span>o<\/b><\/span><\/span><\/sup>)\/cos30<\/b><\/span><\/span>o<\/b><\/span><\/span><\/sup>\u00a0 —\u00a0 d=(2\u221a3.1\/2)\/\u221a3\/2\u00a0 —\u00a0 d=2cm – correta<\/b><\/span><\/span><\/p>\n

(08) Correta\u00a0 —\u00a0 n=C\/V\u00a0 —\u00a0 como C \u00e9 constante, n \u00e9 inversamente proporcional a V.<\/b><\/span><\/span><\/p>\n

(16) Correta \u2013 em toda incid\u00eancia normal, o raio de luz n\u00e3o sofre desvio.<\/b><\/span><\/span><\/p>\n

19-<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/span>Interface n<\/b><\/span><\/span>1<\/b><\/span><\/span><\/sub>\u00a0\u2013 n<\/b><\/span><\/span>2<\/b><\/span><\/span><\/sub>\u00a0 —\u00a0 n<\/b><\/span><\/span>1<\/b><\/span><\/span><\/sub>.sen \u03b8<\/b><\/span><\/span>1<\/b><\/span><\/span><\/sub>=n<\/b><\/span><\/span>2<\/b><\/span><\/span><\/sub>.senr\u00a0 —\u00a0 2.sen \u03b8<\/b><\/span><\/span>1<\/b><\/span><\/span><\/sub>=1,5.senr\u00a0 —\u00a0 senr=2.sen \u03b8<\/b><\/span><\/span>1<\/b><\/span><\/span><\/sub>\/1,5\u00a0 I<\/b><\/span><\/span><\/p>\n

\"\"<\/p>\n

Interface n<\/b><\/span><\/span>2<\/b><\/span><\/span><\/sub>\u00a0\u2013 ar\u00a0 —\u00a0 c\u00e1lculo do \u00e2ngulo limite L\u00a0 —\u00a0 senL=n<\/b><\/span><\/span>menor<\/b><\/span><\/span><\/sub>\/n<\/b><\/span><\/span>maior<\/b><\/span><\/span><\/sub>=1\/1,5\u00a0 —\u00a0 para que haja reflex\u00e3o total nessa interface o raio de luz deve incidir nela com um \u00e2ngulo r tal que r>L, ou seja, senr>senL\u00a0 —\u00a0 senr>1\/1,5\u00a0 II\u00a0 —\u00a0 substituindo I em II\u00a0 —\u00a0<\/b><\/span><\/span><\/p>\n

2.sen \u03b8<\/b><\/span><\/span>1<\/b><\/span><\/span><\/sub>\/1,5 > 1\/1,5\u00a0 —\u00a0 sen \u03b8<\/b><\/span><\/span>1<\/b><\/span><\/span><\/sub>>1\/2\u00a0 —\u00a0\u00a0\u03b8<\/b><\/span><\/span>1<\/b><\/span><\/span><\/sub>>30<\/b><\/span><\/span>o<\/b><\/span><\/span><\/sup>\u00a0 —\u00a0 para qualquer valor de \u03b8<\/b><\/span><\/span>1<\/b><\/span><\/span><\/sub>\u00a0maior que 30<\/b><\/span><\/span>o<\/b><\/span><\/span><\/sup>, o raio de luz sofrer\u00e1 reflex\u00e3o total na interface n<\/b><\/span><\/span>2<\/b><\/span><\/span><\/sub>\u00a0\u2013 n<\/b><\/span><\/span>1<\/b><\/span><\/span><\/sub>.<\/b><\/span><\/span><\/p>\n

20-<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/span>Observe a figura abaixo:<\/b><\/span><\/span><\/p>\n

\"\"<\/p>\n

tg45<\/b><\/span><\/span>o<\/b><\/span><\/span><\/sup>=OC\/d\u00a0 —\u00a0 1=(1 + OB)\/4\u00a0 —\u00a0 4=1 + OB\u00a0 —\u00a0 OB=3cm\u00a0 —\u00a0 (AB)<\/b><\/span><\/span>2<\/b><\/span><\/span><\/sup>= d<\/b><\/span><\/span>2<\/b><\/span><\/span><\/sup>\u00a0+ (OB)<\/b><\/span><\/span>2<\/b><\/span><\/span><\/sup>\u00a0 —\u00a0 (AB)<\/b><\/span><\/span>2<\/b><\/span><\/span><\/sup>= (4)<\/b><\/span><\/span>2<\/b><\/span><\/span><\/sup>\u00a0+ (3)<\/b><\/span><\/span>2<\/b><\/span><\/span><\/sup>\u00a0\u00a0 —\u00a0 AB=5cm\u00a0 —\u00a0 senr=OB\/AB\u00a0 —\u00a0 senr=3\/5\u00a0 —\u00a0 aplicando Snell-Descartes na face superior\u00a0 —\u00a0 n<\/b><\/span><\/span>ar<\/b><\/span><\/span><\/sub>.sen45<\/b><\/span><\/span>o<\/b><\/span><\/span><\/sup>=n.senr\u00a0 —\u00a0 1.\u221a2\/2=n.3\/5\u00a0 —\u00a0\u00a0n=5\u221a2\/6<\/b><\/span><\/span><\/p>\n

21-<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/span>Lei de Snell\u00a0 —\u00a0 n<\/b><\/span><\/span>1<\/b><\/span><\/span><\/sub>.seni = n<\/b><\/span><\/span>2<\/b><\/span><\/span><\/sub>.senr\u00a0 —\u00a0 (1).(\u221a3\/ 2) = (\u221a3).senr\u00a0 —\u00a0 sen r =1\/2\u00a0 —\u00a0 \u00a0r = 30 \u00ba\u00a0 —\u00a0 no interior da l\u00e2mina voc\u00ea obt\u00e9m um<\/b><\/span><\/span><\/p>\n

\"\"<\/p>\n

triangulo ret\u00e2ngulo\u00a0 —\u00a0 d = cateto oposto\u00a0 —\u00a0 4\u221a3 = cateto adjacente\u00a0 —\u00a0 tg30<\/b><\/span><\/span>o<\/b><\/span><\/span><\/sup>=cateto oposto\/cateto adjacente\u00a0 —\u00a0 tg30<\/b><\/span><\/span>o<\/b><\/span><\/span><\/sup>=d \/ 4 \u221a3 —\u00a0 d \/ 4 \u221a3 = \u221a3 \/ 3\u00a0 — 3d = 4.\u221a3.\u221a3\u00a0 —\u00a0 d = 12\/3\u00a0 —\u00a0\u00a0d = 4\u00a0cm\u00a0<\/b><\/span><\/span><\/p>\n

22-<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/span>n<\/b><\/span><\/span>ar<\/b><\/span><\/span><\/sub>=1\u00a0 —\u00a0 n<\/b><\/span><\/span>vidro<\/b><\/span><\/span><\/sub>\u00a0=\u00a0\"\"\u00a0—\u00a0 \u00a0e =\u00a0\"\"cm\u00a0 —\u00a0 como o \u00e2ngulo entre o raio e a l\u00e2mina \u00e9 de 30\u00b0, o \u00e2ngulo de incid\u00eancia \u00e9: i = 60\u00b0\u00a0 —\u00a0<\/b><\/span><\/span><\/p>\n

o raio provem do ar, atravessa a l\u00e2mina e volta para o ar, o raio emergente \u00e9 paralelo ao incidente\u00a0 —\u00a0 i\u2019 = i = 60\u00b0\u00a0 —\u00a0 observe a<\/b><\/span><\/span><\/p>\n

\"\"<\/p>\n

figura\u00a0 —\u00a0 lei de Snell na primeira face\u00a0 —\u00a0 n<\/b><\/span><\/span>ar\u00a0<\/b><\/span><\/span><\/sub>sen<\/b><\/span><\/span>\u00a0<\/b><\/span><\/span><\/sub>i = n<\/b><\/span><\/span>vidro\u00a0<\/b><\/span><\/span><\/sub>sen<\/b><\/span><\/span>\u00a0<\/b><\/span><\/span><\/sub>r\u00a0 —\u00a0 \u00a0(1)<\/b><\/span><\/span>\u00a0<\/b><\/span><\/span><\/sub>sen<\/b><\/span><\/span>\u00a0<\/b><\/span><\/span><\/sub>60\u00b0 =\u00a0\"\"senr\u00a0 — \u221a3\/2 = \u221a3sen r\u00a0 —\u00a0 sem r = \u00bd\u00a0 —\u00a0<\/b><\/span><\/span><\/p>\n

r = 30<\/b><\/span><\/span>o<\/b><\/span><\/span><\/sup>\u00a0 —\u00a0 no ponto\u00a0<\/b><\/span><\/span>C\u00a0 —\u00a0\u00a0<\/b><\/i><\/span><\/span>\u00a0os \u00e2ngulos\u00a0\"\"\u00a0e r s\u00e3o alternos-internos\u00a0 —\u00a0\u00a0\"\"= 30\u00b0\u00a0 —\u00a0 \u00a0os \u00e2ngulos\u00a0\"\"e i\u2019 s\u00e3o opostos pelo v\u00e9rtice\u00a0 —\u00a0\u00a0\"\"= 60\u00b0\u00a0 —\u00a0\u00a0\"\"=\"\"\u00a0+\u00a0\"\"<\/b><\/span><\/span>\u00a0—\u00a0\u00a0<\/b><\/span><\/span><\/sub>60\u00b0 = 30\u00b0 +\u00a0\"\"—\u00a0\u00a0\"\"= 30\u00b0\u00a0 —\u00a0 no tri\u00e2ngulo\u00a0<\/b><\/span><\/span>ABC<\/b><\/i><\/span><\/span>\u00a0 —\u00a0 c\u00f3s 30<\/b><\/span><\/span>o<\/b><\/span><\/span><\/sup>=BC\/AC\u00a0 —\u00a0 \u221a3\/2 = \u221a3\/AC\u00a0 —\u00a0 AC=2cm\u00a0 —\u00a0 no tri\u00e2ngulo\u00a0<\/b><\/span><\/span>ACD<\/b><\/i><\/span><\/span>\u00a0 —\u00a0 sen30<\/b><\/span><\/span>o<\/b><\/span><\/span><\/sup>=AD\/AC\u00a0 —\u00a0 1\/2=x\/2\u00a0 —\u00a0\u00a0x=1cm<\/b><\/span><\/span><\/p>\n

23-<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/span>Observe o trajeto feito pelo raio luminoso\u00a0 — os \u00e2ngulos 1 e 2 s\u00e3o iguais (alternos internos)\u00a0 —\u00a0 os \u00e2ngulos 2 e 3 s\u00e3o iguais<\/b><\/span><\/span><\/p>\n

\"\"<\/p>\n

\"\"<\/p>\n

 <\/p>\n

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

A frequ\u00eancia \u00e9 caracter\u00edstica da onda (no caso, luz)\u00a0 —\u00a0 quando a luz de determinada frequ\u00eancia se refrata passando de um meio para outro, sua velocidade de propaga\u00e7\u00e3o e seu comprimento de onda variam, mas sua frequ\u00eancia permanece a mesma, independente do meio em que estiver se propagando\u00a0 —\u00a0 assim, as alternativas A, B e C est\u00e3o erradas.<\/b><\/span><\/span><\/p>\n

A correta \u00e9 a D, pois, quanto mais refringente \u00e9 o meio, maior ser\u00e1 o valor de seu \u00edndice de refra\u00e7\u00e3o n, \u00a0menor a velocidade da luz nesse meio e maior ser\u00e1 o desvio sofrido.<\/b><\/span><\/span><\/p>\n

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

Aplicando a lei de Snell\u00a0 —\u00a0 n<\/b><\/span><\/span>1<\/b><\/span><\/span><\/sub>.sen\u03b8<\/b><\/span><\/span>1<\/b><\/span><\/span><\/sub>\u00a0= n<\/b><\/span><\/span>2<\/b><\/span><\/span><\/sub>.sen\u03b8<\/b><\/span><\/span>2<\/b><\/span><\/span><\/sub>\u00a0 — \u00a01.sen60<\/b><\/span><\/span>o<\/b><\/span><\/span><\/sup>\u00a0= \u221a3.sen.\u03b8<\/b><\/span><\/span>2<\/b><\/span><\/span><\/sub>\u00a0 —\u00a0 1.\u221a3\/2 = \u221a3.sen \u03b8<\/b><\/span><\/span>2<\/b><\/span><\/span><\/sub>\u00a0 —\u00a0 sen \u03b8<\/b><\/span><\/span>2<\/b><\/span><\/span><\/sub>=1\/2\u00a0 —\u00a0 \u03b8<\/b><\/span><\/span>2<\/b><\/span><\/span><\/sub>=30<\/b><\/span><\/span>o<\/b><\/span><\/span><\/sup>\u00a0 —<\/b><\/span><\/span><\/p>\n

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

 <\/p>\n

\u00a0Voltar para os exerc\u00edcios<\/span><\/a><\/h3>\n","protected":false},"excerpt":{"rendered":"

Resolu\u00e7\u00e3o comentada dos exerc\u00edcios de vestibulares sobre L\u00e2minas de faces paralelas 01- Lei de Snell-Descartes – A rela\u00e7\u00e3o entre o seno do \u00e2ngulo de incid\u00eancia e o seno do \u00e2ngulo de refra\u00e7\u00e3o \u00e9 uma grandeza constante denominada \u00edndice de refra\u00e7\u00e3o do segundo meio em rela\u00e7\u00e3o ao primeiro, ou seja,\u00a0 seni\/senr=n2\/n1\u00a0\u00a0\u00a0 As express\u00f5es acima nos mostram que quando a luz passar<\/p>\n","protected":false},"author":1,"featured_media":0,"parent":2217,"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-2221","page","type-page","status-publish","hentry"],"aioseo_notices":[],"_links":{"self":[{"href":"https:\/\/fisicaevestibular.com.br\/novo\/wp-json\/wp\/v2\/pages\/2221","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=2221"}],"version-history":[{"count":3,"href":"https:\/\/fisicaevestibular.com.br\/novo\/wp-json\/wp\/v2\/pages\/2221\/revisions"}],"predecessor-version":[{"id":10945,"href":"https:\/\/fisicaevestibular.com.br\/novo\/wp-json\/wp\/v2\/pages\/2221\/revisions\/10945"}],"up":[{"embeddable":true,"href":"https:\/\/fisicaevestibular.com.br\/novo\/wp-json\/wp\/v2\/pages\/2217"}],"wp:attachment":[{"href":"https:\/\/fisicaevestibular.com.br\/novo\/wp-json\/wp\/v2\/media?parent=2221"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}