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. `2 sin^(-1)(1//n)`

Answer

B

Explanation

Diverging angle will remain unchanged because in case of glass slab every emergent ray is parallel to the incident ray . However , the rays are displaced slightly towards outer side .

(In the figure `OA||BC "and" OD||EF`)