question_answer

The angle of a prism is A. One of its refracting surfaces is silvered. Light rays falling at an angle of incidence 2 A on the first surface returns back through the same path after suffering reflection at the silvered surface. The refractive index \[\mu ,\] of the prism is                                       [NEET 2014]

A)  \[2\sin A\]

B)       \[2\cos A\]

C)  \[\frac{1}{2}\cos A\]     

D)       \[\tan A\] 

Correct Answer: B

Solution :

For the given condition above ray diagram will sift.

So

By Snell's law

Þ