Question

A ray of light makes an angle of ${10}^{\circ }$ with the horizontal above it and strikes a plane mirror which is inclined at an angle $\theta$ to the horizontal. The angle $\theta$ for which the reflected ray becomes vertical is

• A. ${40}^{\circ }$
• B. ${50}^{\circ }$
• C. ${80}^{\circ }$
• D. ${100}^{\circ }$

Answer 1

The correct option is A ${40}^{\circ }$

From figure
$\theta +\theta +10=90\Rightarrow \theta ={40}^{\circ }$