Question

Two plane mirrors, each of length $2\sqrt{3m}$, are placed parallel to each other at a dist of $0.2m$. A light ray is incident on $1mirror$ at an angle of ${30}^o$ as shown, then after how many reflections, the light ray will emerge out of mirror ?

Answer 1

$2\sqrt{3}m$

$\angle i=\angle r$ [Law of Reflection].

$\frac{x}{0.2}=\tan {30}^{\circ }$

$\Rightarrow x=\frac{0.2}{\sqrt{3}}$

No. of reflections by light before coming out $=\frac{Totallengthtobecovered}{distancetraveledinonereflection}$

$=\frac{2\sqrt{3}}{\frac{0.2}{\sqrt{3}}}$

$=30$

$\Rightarrow$ No. of reflections $=30$