Question

An incident ray makes an angle of ${65}^{\circ }$ with the surface of a plane mirror. The angle of reflection in this case will be:

(a) ${65}^{\circ }$

(b) ${45}^{\circ }$

(c) ${25}^{\circ }$

(d) ${35}^{\circ }$

Answer 1

Answer: (c) ${25}^{\circ }$

If an incident ray makes an angle of ${65}^{\circ }$ with the surface of a plane mirror then it makes an angle of ${90}^{\circ }-{65}^{\circ }={25}^{\circ }$ with the normal at the point of the incidence. Which is known as the angle of incidence.

Now according to the law of reflection, the angle of incidence is equal to the angle of reflection. Therefore angle of reflection is equal to ${25}^{\circ }$.