Two vertical plane mirrors are joined at a right angle. A horizontal beam of light is shone on one of the mirrors at an angle of incidence of 22 degrees, such that the reflected ray strikes the other mirror. What is the angle of incidence of the beam that strikes the second mirror?
A) 23°
B) 68°
C) 43°
D) 22°

Question

Quizplus · Accepted Answer

When a light ray hits a mirror, the angle of incidence is equal to the angle of reflection. Therefore, the angle of reflection on the first mirror is also 22°. Since the mirrors are joined at a right angle, the reflected ray from the first mirror becomes the incident ray for the second mirror, making the angle of incidence on the second mirror 90° - 22° = 68°. The correct answer is therefore B.

Two Vertical Plane Mirrors Are Joined at a Right Angle