Question

Write two essential conditions for total internal reflection to occur

Answer 1

the light is in the more dense medium and approaching the less dense medium.

the angle of incidence is greater than the so-called critical angle.

Answer 2

The two conditions for total internal reflection :
1. The ray of light must travel from a denser medium into a rarer medium.
2. The angle of incidence in the denser medium must be greater than the critical angle for that pair of media.