Question

hi plz answer this Q
1. Aray of light passes from vacuum into a medium of
refractive index u, the angle of incidence is found
to be twice the angle of refraction. Then the angle
of incidence is
(A) cos-1 (u/2)
(B) 2cos-(u/2)
(C) 2sin- u
(D) 2sin-'(u/2)
Please answer with explanation,images. And will mark u as branliest.​

Answer 1

Answer:

Explanation:

Let i be the incident angle and r be the refracted angle

given,  1=2r⇒r= i/2

 

the refractive index of vacuum is 1 and that of another medium is n from snell's law.

1sin i = n sin r

⇒ sin i = n sin (i/2)

2 sin (i/2) cos (i/2) = n sin (i/2)

    => sin (i/2) (2 cos (i/2) - n = 0

sin (i/2) = 0 = sin π ⇒ i = 2π

(2 cos (i/2) - n ) = 0 ⇒ i = 2 cos to the power - 1 (n/2)

therefore the value of incident angle = 2 cos to the power -1  (n/2)

Hope you have understand.

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