Question

Two plane mirrors meet at a right angle ( see Fig.). An incident ray strikes the bottom mirror at point B with an angle of incidence theta _i; this ray reflects from each mirror and strikes the screen on top at point A. The screen is parallel to the bottom mirror. Given the dimensions in Figure, what is theta_i?

Answer 1

Answer:

Angle of deviation in such cases are given as

δ=360°−2θ

asθ=90°

∴δ=360°−2×90°=180°

As angle of deviation is 180°, it means the reflected ray from second mirror will be parallel to that incident on the first mirror.