When light propagates to the interface between two different media, a portion of the light returns to the original medium. This phenomenon is known as the reflection of light. The reflection of light follows these laws:

• The incident ray, the reflected ray, and the normal all lie in the same plane.
• The reflected ray and the incident ray are on opposite sides of the normal.
• The angle of reflection is equal to the angle of incidence (\(\theta _{r}=\theta _{i}\)).

Here, the normal is an imaginary line perpendicular to the interface, and both the angle of incidence and the angle of reflection are measured between the respective rays and the normal.

Image Formation by a Plane Mirror
When we look into a mirror, the image we see is a direct result of the law of reflection. Every point on an object emits light rays in all directions. When these rays strike a smooth mirror surface, they are reflected according to the law of reflection, and the resulting virtual image points together form the complete virtual image of the object.