Question

State the condition required for total internal refraction of light takes place.

Answer 1

1. When a ray of light goes from denser medium to rarer medium, it bends away from the normal.
2. As angle of incidence in dense medium increases, the angle of refraction in the rare medium also increase ${90}^{°}$. This is called Critical Angle.
3. When the angle of incident in the denser medium exceeds the critical angle, then gets reflected back in the denser medium and this phenomenon is called total internal reflection.
4. There are two conditions necessary for the the total internal reflection to take place:-

(i) The ray must travel from denser medium to rarer medium.

(ii) the angle of incidence (i) should be greater than critical angle C.