Question

Two plane mirrors are inclined to each other such that a ray of light incident on the first mirror $\left(M_1\right)$ and parallel to the second mirror $\left(M_2\right)$ is finally reflected from the second mirror $\left(M_1\right)$ parallel to the two mirroes will be :

• A. ${90}^0$
• B. ${75}^0$
• C. ${45}^0$
• D. ${60}^0$

Answer 1

The correct option is D ${60}^0$

$\begin{array}{c}\text{Assuming angles between two mirrors be}\theta \text{.}\\ \text{we know that angle made by light ray for incidence}\\ \text{and reflection with mirror is same.}\\ \text{Now by geometry}\\ \begin{array}{c}\text{Sum of angles in a triangle}={180}^{\circ }\\ 30={180}^{\circ }\\ \theta ={60}^{\circ }\end{array}\end{array}$