Question

What is the critical angle for a diamond-air interface? What happens if a ray of light is incident at angles of 20degrees, 24degrees and 50degrees?

Answer 1

Given

Refractive index of diamond is n=2.42

The critical angle for a diamond-air interface is

$\theta_c=sin^{-1}(\frac{1}{n}) =sin^{-1}(\frac{1}{2.42})=24.4^{o}$

For incident angle $20^{o}$ , the light ray refracted into air medium because angle of incident is less than the critical angle.

For incident angle $24^{o},$ the light ray refracted into air medium because angle of incident is less than the critical angle.

For incident angle $50^{o}$ , the light ray under goes internal reflection in the diamond because angle of incident is greater than the critical angle.