Question

Which of the following conditions are necessary for total internal reflection to take place at the boundary of two optical media ?
1. Light is passing from optically denser medium to optically rarer medium.
2. Light is passing from optically rarer medium to optically denser medium.
3.Angle of incidence is greater than the critical angle.
4.Angle of incidence is less than the critical angle.

• A. 1 and 3 only
• B. 2 and 4 only
• C. 3 and 4 only
• D. 1 and 4 only

Answer 1

The correct option is A 1 and 3 only

Total internal reflection (TIR) is the phenomenon that involves the reflection of all the incident light off the boundary. TIR only takes place when both of the following two conditions are met:
(1)The light is in the more dense medium and approaching the less dense medium.
(2)The angle of incidence is greater than the so-called critical angle.
Hence, option A is correct.