$\"\"$

A light beam passes through a thick slab of material, then index of refraction is $\"\"$ .

When a light beam passed through a thick slab, it reflects from the smooth surface to the same medium.

Hence $\"\"$ .

$\"\"$

$\"\"$ .

The angle of the scattered rays equals the angle of the incoming rays. \ \

Thus, $\"\"$ is the angle of refraction of the emerging beam. \ \

$\"\"$

$\"\"$ is the angle of refraction of the emerging beam.