Question

A ray of light is incident on the face of an equilateral prism at angle of 90°. The ray gets totally reflected on the second refracting face. The total deviation produced in the path of ray is:

Options

• 60°

• 90°

• 120°

• 180°

Answer 1

120°

Explanation:

The ray enters normally and travels undeviated inside the prism. It undergoes total internal reflection at the second face and emerges from the other face, producing a total deviation of 120°. The other listed angles are not the deviation for this path.