A plane mirror is plane light reflecting surface (normally glass the other surface of which is coated a thin layer of silver metal.
A ray of light is the stAraight line along which the light travels.
A ray of light which falls on a mirror is called the incident ray.
A ray of light which is sent or reflected back by the miror is called reflected ray.
Normal is a line drawn perpendicular to the surface of mirror from point the point where incident ray meets the surface of the mirror.
The angle of incidence is the angle the incident ray makes with the normal drawn at the point of incidence of the incident ray on he surface of the mirror.
The angle of reflection is the angle the reflected ray makes with the normal drawn at the point of incidence.
Reflection is the return of a wave of energy such as light or radio wave or sound after it strikes a surface intercepting its path. Though this term is used for many different types of waves we will refer to only light waves in rest to this discussion.
The reflection of light ray resembles ate bouncing back of a ball hitting a smooth surface. To understand explain the nature of reflection we need to define some related terms. These include normal, angle of incidence, and angle of reflection.
Normal is an imaginary line perpendicular to the surface reflecting the light. the angle between the path of the incoming ray of light and the normal is called angle of incidence, and the angle that the reflected ray makes with the normal is called angle of reflection. The angle of reflection is always equal to the angle of incidence.