A ray of light strikes a plane mirror at an angle of incidence of 35°. If the mirror is rotated through 10°; through what angle is the reflected ray rotated?

A. 70°
B. 45°
C. 25°
D. 20°

Correct Answer:

Option D = 20°

Explanation

Whenever a ray of light is incident on a plane mirror at an angle of incidence l, if the mirror is then rotated through an angle θ, then the reflected ray is rotated through an angle twice θ

So if θ = 35°, then the reflected ray is rotated through 2 x 10° = 20°