A diverging beam of light from a point source S having divergence angle α 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 its refractive index is n, then the divergence angle of the emergent beam is

Question

A diverging beam of light from a point source S having divergence angle α 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 its refractive index is n, then the divergence angle of the emergent beam is (A) zero (B) α (C) sin-1 (1/n) (D) 2sin-1 (1/n)

Tardigrade Admin · Accepted Answer

Divergence angle will remain unchanged because in case of a
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)

zero

$α$

$s i n^{- 1} (1/ n)$

$2 s i n^{- 1} (1/ n)$

Divergence angle will remain unchanged because in case of a
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)

zero

α

sin−1(1/n)

2sin−1(1/n)

Divergence angle will remain unchanged because in case of a 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)

$α$

$s i n^{- 1} (1/ n)$

$2 s i n^{- 1} (1/ n)$

Divergence angle will remain unchanged because in case of a
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)