Question

If a ray incidents normally on a plane mirror, what will be the angle of reflection

Answer 1

In case of reflection and refraction, angle is always measured from the normal to the incident point.
So, when ray incidents normally, that means angle is 0° . And according to the law of reflection,
∠i = ∠r
so, angle of reflection will be 0° that means it is reflected back on the same path. 

Answer 2

Answer:

Explanation:

When the light ray is incident normally on the plane mirror then by using laws of reflection angle of incidence is equal to angle of reflection.

Hence, as the angle of incidence is zero degree angle of reflection is zero degree.