Q. A diverging beam of light from a point source 5 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) $\sin^{- 1}{(1/n)}$
D) $2\sin^{- 1}{(1/n)}$
Explanation
(b) Since rays after passing through the glass slab just suffer lateral displacement hence we have angle between the emergent rays as $\alpha$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.