Ncert Exercises & Solutions

A ray of light incident at an angle $θ$ on a refracting face of a prism emerges from the other face normally. If the angle of the prism is 5 $°$ and the prism is made of a material of refractive index 1.5, the angle of incidence is:

1. 7.5 $°$
2. 5 $°$
3. 15 $°$
4. 2.5 $°$

(1) Hint: The angle of refraction at the second surface is equal to zero.

Step 1: Find the angle of deviation.

Since deviation $δ = (μ - 1) A = (1.5 - 1) \times 5 ° = 2.5 °$

Step 2: Find the angle of incident.

By geometry, the angle of refraction by the first surface is 5 $°$ .

But $δ = θ - r$ , so, we have, 2.5 $°$ = $θ$ - 5 $°$ , on solving $θ$ = 7.5 $°$ .

NEET Information

courses

Company

Botany Questions

Chemistry Questions

Physics Questions

Zoology Questions