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

(A) zero

(B) α

(C) sin^{–1} (1/n)

(D) 2 sin^{–1} (1/n)

Ans: (B)