Two flat rectangular mirrors are set edge to edge and placed perpendicular to a flat nonreflecting surface. The edges of the two mirrors meet at a 30° angle. A light ray that approaches mirror 1 is parallel to mirror 2. The angle of reflection of that ray from mirror 1 is
A) 0°.
B) 30°.
C) 60°.
D) 90°.
E) 120°.

Question

Quizplus · Accepted Answer

The light ray approaches mirror 1 parallel to mirror 2, which means it makes a 60° angle with the normal to mirror 1 (since the mirrors meet at a 30° angle). By the law of reflection, the angle of reflection equals the angle of incidence, so the angle of reflection is 60°.

Two Flat Rectangular Mirrors Are Set Edge to Edge and Placed