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Question: Answered & Verified by Expert
Let the refractive index of a denser medium with respect to rarer medium be n12 and its critical angle be θC . At an angle of incidence A when light is travelling from denser medium to rarer medium, a part of the light is reflected and the rest is refracted and the angle between reflected and refracted rays is 90o. Angle A is given by 
PhysicsRay OpticsJEE MainJEE Main 2017 (08 Apr Online)
Options:
  • A tan-1sinθC
  • B 1tan-1sinθC
  • C cos-1sinθC
  • D 1cos-1sinθC
Solution:
2842 Upvotes Verified Answer
The correct answer is: tan-1sinθC



In accordance with Snell's law, μ=μRμD=sinicsin90o

here ic is the angle of incidence.

μRμD=sinic

μ=μRμD=sinAsinr

=sinAsin90°-A=sinAcosA

μRμD=tanA.

The critical angle is related to the angle A as tanA=sinθC

A=tan-1sinθC.

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