Question

A light ray is incident on a plane mirror and the angle of reflection is ${50}^{\circ }$. Calculate the angle between the incident ray and the reflected ray.

• A. ${25}^{\circ }$
• B. ${50}^{\circ }$
• C. ${80}^{\circ }$
• D. ${90}^{\circ }$

Answer 1

The correct option is C ${80}^{\circ }$

Given,
Angle of reflection, $r={50}^{\circ }$

We are required to find the angle between the incident ray and the reflected ray. So, we need to find the angle between AO and OC. For this, we will have to extend AO to B. The angle we need to find is $\angle BOC$.

Using laws of reflection, $\angle AON=\angle NOC={50}^{\circ }$

Finally,
$\angle AON+\angle NOC+\angle COB={180}^{\circ }$
${50}^{\circ }+{50}^{\circ }+\angle COB={180}^{\circ }$
$\angle BOC={80}^{\circ }$