When two plane mirrors subtend an angle between them

PHYSICS · Single correct · CBSE · Physics · Light — Reflection and Refraction · Light — Reflection and Refraction

Problem

When two plane mirrors subtend an angle

\theta

between them, a ray of light incident parallel to one of them retraces its path after

n

reflections such that

n\theta=c

, where

c

is a constant. What is the value of

c

? (a)

\pi

(b)

\frac{\pi}{2}

(c)

\frac{3\pi}{2}

(d) None of these