Question

State and explain the laws of reflection of light at a plane surface (like a plane mirror), with the help of a labelled ray-diagram. Mark the angles of 'incidence' and 'reflection' clearly on the diagram. If the angle of reflection is ${47.5}^{\circ }$, what will be the angle of incidence ?

Answer 1

The reflection of light follows the following two laws of reflection:

• The incident ray, the reflected ray, and the normal to the surface of the mirror at the point of incidence all lie in the same plane.
• The angle of reflection is equal to the angle of incidence.

Consider a light-ray incident on a plane mirror, as shown below:

The incident ray (AO), reflected ray (BO) and normal (ON), all lie in the same plane. Moreover, the angle of incidence (${\theta }_i$) is equal to the angle of reflection (${\theta }_r$).

If angle of reflection = ${47.5}^{\circ }$, angle of incidence will also be = ${47.5}^{\circ }$.