What is critical angle and total internal reflection?

The critical angle for total internal reflection in diamond is 24.5^(@) . The refractive index of diamond is

If the critical angle for total internal reflection from a medium to vacuum is 30^(@) , then velocity of light in the medium is

An optical fibre (RI = 1.72) is surrounded by a glass coating (RI= 1.50). Find the critical angle for total internal reflection at the fibre-glass interface.

What is critical day length?

Partial reflection and Total internal reflection.

When a ray of light enter from one medium to another, its velocity is doubled. The critical angle for the ray for two internal reflection will be

Rainbow formation or Prove that a rainbow is the combined effect of the refraction, dispersion and total internal reflection of light.

The reason for brilliance of diamonds is total internal reflection of light.