Physics for IGCSE & O level - Rays And Waves (Section 11 - No. 25)
What must occur for total internal reflection to happen?
The angle of incidence must be less than the critical angle.
Light must be travelling from a less dense medium to a more dense medium.
The angle of incidence must be greater than the critical angle.
The light source must be very dim.
Explication
Total internal reflection occurs when the angle of incidence is greater than the critical angle.