Question

What will be the deviation produced when a ray of light is incident on a plane mirror at an angle of incidence ${60^0}$?
A. ${30^0}$
B. ${90^0}$
C. ${60^0}$
D. ${120^0}$

Answer 1

Hint: In order to solve this question, you must be aware of the laws of reflection. It states that when a ray of light reflects off a surface, the angle of incidence is equal to the angle of reflection. The angle of deviation is the angle between extended incident ray and reflected ray.

Complete step by step answer:
The angle of deviation is defined as the difference between the angle of incidence and the angle of refraction caused by a ray of light travelling from one refractive index medium to another.
Given: Angle of incidence of the ray of light is ${60^0}$.
To find: The angle of deviation produced.
According to the laws of reflection, the angle of incidence is equal to the angle of reflection. It means that the ray will reflect at an angle of ${60^0}$
Angle of deviation,
$\delta = 180 - (i + r)$
$\Rightarrow \delta = 180 - 120$
$\therefore \delta = {60^0}$
Therefore, the angle of deviation is ${60^0}$.

Hence, option C is correct.

Note: Characteristics of the image formed by a plane mirror are that it is virtual and erect and of the same size as the object. The distance of the object from the plane mirror is the same as the distance of the image from the plane mirror. One of the important characteristics of the image is that it is laterally inverted.