Question

What is meant by the term 'critical angle'? How is it related to the refractive index of the medium?

Answer 1

Critical angle:

1. The angle of incidence beyond which rays of light passing through a denser medium to the surface of a less dense medium are no longer refracted but totally reflected.

Mathematically, the relation between the critical angle and the refractive index of the medium can be represented below.

$\left({}^a{\mu }_{\mathrm{g}}\right)=\mathrm{cosec}{\mathrm{i}}_{\mathrm{c}}$

Here,

${}^a{\mu }_{\mathrm{g}}$ is the refractive index of the medium.

${\mathrm{i}}_{\mathrm{c}}$ is the critical angle.