Question

A light ray is incident at an incident angle θ1 on the system of two plane mirrors M1 and M2 having an inclination angle 75° between them (as shown in figure).
After reflecting from mirror M1 it gets reflected back by the mirror M2 with an angle of reflection 30°. The total deviation of the ray will be ________ degree.

Answer 1

On first reflection angel of deviation is 90° and on second reflection angle of deviation is 120°

so total deviation is $δ = 90° +120° = 210°$