Question

A light ray is incident, at an incident angle ${\theta }_1$, on the system of two plane mirrors $M_1$ and $M_2$ having an inclination angle $75^{\circ }$ between them (as shown in figure). After reflecting from mirror $M_1$ it gets reflected back by the mirror $M_2$ with an angle of reflection $30^{\circ }$. The total deviation of the ray will be .............. degree.

Answer 1

Answer: 210

${\delta }_{\text{total }}=360^{\circ }-2\theta$
$=360^{\circ }-2\times 75^{\circ }$
${\delta }_{\text{totakl }}=210^{\circ }$

${\theta }_1=45^{\circ }$

$\delta =120^{\circ }+90^{\circ }=210^{\circ }$