question_answer

A diverging beam of light from a point source S having divergence angle\[\alpha \], falls symmetrically on a glass slab as shown. The angles of incidence of the two extreme rays are equal. If the thickness of the glass slab is t and the refractive index n, then the divergence angle of the emergent beam is

A) zero

B) \[\alpha \]

C) \[{{\sin }^{-1}}\left( \frac{1}{n} \right)\]  

D) \[2{{\sin }^{-1}}\left( \frac{1}{n} \right)\]