Physics for IGCSE & O level - Rays And Waves (Section 11 - No. 3)
Which of the following is a necessary condition for total internal reflection to occur?
Light must be traveling from a less dense to a more dense medium
Light must be traveling from a more dense to a less dense medium
The angle of incidence must be less than the critical angle
The angle of incidence must be equal to the critical angle
Explication
Total internal reflection requires light to be traveling from a more dense to a less dense medium.