Two plane mirrors and are fixed mutually perpendicular to each other along a common edge
PHYSICS · Subjective · CBSE · Physics · Light — Reflection and Refraction · Light — Reflection and Refraction
Problem
Two plane mirrors M1 and M2 are fixed mutually perpendicular to each other along a common edge. A light ray lying in a plane normal to the line of intersection of the mirrors strikes M1 such that it makes an angle of 15∘ with the mirror surface.
(a) Determine the angle of incidence on M1 and hence the direction of the ray after its first reflection.
(b) The reflected ray from M1 now strikes M2. Calculate the angle of incidence on M2.
(c) Find the angle made by the ray emerging after reflection from M2 with respect to its original incident direction.
(d) Show analytically that, for any ray incident on such a pair of perpendicular plane mirrors, the final emergent ray is rotated through twice the angle the initial incident ray makes with the line of symmetry of the mirror arrangement.