'During refraction of light through the glass slab, incident ray and emergent ray are parallel to each other.' Explain.

Explanation

i. Refraction oflight talces place twice in a glass slab.
ii. The first refraction occurs when light enters the glass from air. The second refraction occurs when light enters air from glass.
iii. The angle of incident of the light ray is equal to the angle of emergence.
iv. On both the parallel sides of the glass slab, the change in direction of light ray is equal but in opposite directions.
v. Thus, the light ray emerging from the glass slab is parallel to the incident ray.