Question

A ray of light is reflected by two mirrors placed normal to each other. The incident ray makes an angle of ${22}^{\circ }$ with one of the mirrors. At what angle $\theta$ (in degree) does the ray emerge?

Answer 1

Angle of deviation $\delta ={360}^{\circ }–2\theta$
$={360}^{\circ }-2\left({90}^{\circ }\right)$
$={180}^{\circ }$
Reflected ray is antiparallel to incident ray $\varphi ={90}^{\circ }-{22}^{\circ }={68}^{\circ }$