Question

What are the conditions for total internal reflection?

Answer 1

Total internal reflection

Whenever a ray of light goes from an optically denser medium to a rarer medium, being incident at an angle larger than just the critical angle of the media then, the ray completely reflects back further into the medium. This is referred to as complete internal reflection.

The condition for total internal reflection

The two conditions for the total internal reflection to take place are as follows:

1. Throughout the denser medium, the angle of incidence must've been larger than the critical angle for this kind of combination of media.
2. A light ray might move from a denser medium toward a rarer medium.

The critical angle is defined as the angle of incidence in a denser media where the angle of refraction inside a rarer medium approaches 90°.