Question

When a prism is in minimum deviation position, the value of angle of incidence is equal to:

Options

• \(\dfrac{\angle \mathrm{A} + \angle \delta}{2}\)

• \((\angle \mathrm{A}+\angle \delta) \times 2\)

• \(\dfrac{2}{\angle \mathrm{A} + \angle \delta}\)

• none of these

Answer 1

\(\dfrac{\angle \mathrm{A} + \angle \delta}{2}\)

Explanation:

At minimum deviation, the angle of incidence equals the angle of emergence.

Using the prism relation $$\angle \mathrm{A} + \angle \delta = \angle i + \angle e$$, we get $$\angle i = \dfrac{\angle \mathrm{A} + \angle \delta}{2}.$$