Question

A beam of monochromatic light is incident at an angle of incidence of 50° on one face of an equilateral prism. If the angle of emergence is 40°, what will be the angle of minimum deviation?

Answer 1

Given:

Angle of incidence (i) = 50°

Angle of emergence (e) = 40°

Angle of an equilateral prism (A) = 60° (Since an equilateral triangle has angles of 60°)

Formula:

A + δ = i + e

δ = i + e − A

= 50° + 40° − 60°

= 90° − 60°

= 30°

The angle of deviation is 30°.