Question

A ray of light on a concave mirror of radius of curvature '$R$' at a height $\frac{\sqrt{3}}{2}R$ from the principal axis as shown. The net deviation in ray caused by the mirror is:

• A. $\frac{2\pi }{3}$
• B. $\pi$
• C. $\frac{\pi }{2}$
• D. $\frac{\pi }{6}$

Answer 1

The correct option is A $\frac{2\pi }{3}$

$\begin{array}{c}\text{In}△CHL\sin \theta =\frac{\frac{\sqrt{3R}}{2}}{R}\Rightarrow \theta ={60}^{\circ }=\frac{\pi }{3}\\ \delta \text{(Deviation)}=\pi -i=\pi -\frac{\pi }{3}=\frac{2\pi }{3}\\ \text{So}S=\frac{2\pi }{3}\text{option}A\text{is the answer.}\end{array}$