A diverging beam of light from a point source S having devergence 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

Options

A. zero
B. `alpha`
C. `sin^(-1)1/n`
D. `2sin^(-1)(1/n)`

Answer

B

Explanation

(b) Since, rays after passing through the glass slab just suffer lateral displacement. So, angle between emergent ray is also `alpha`.