Why do we draw a normal between the reflected ray and the incident ray? What does a normal represents??

Question

Leo Abeyta · Accepted Answer

Refer to the figure above. A ray of light is incident on a totally reflecting surface (mirror) at a certain point.

This point is called point of incidence.

If we draw a line which is perpendicular to the reflecting surface at the point of incidence, this line is called the normal.

As such it is an imaginary line perpendicular to the surface reflecting the light.

Angle between the incident ray and the normal is called angle of incidence. Shown as #angle theta#.

Angle between the reflected ray and the normal is called angle of reflection. Shown as #angle theta'#

The law of reflection states that when a ray of light is reflected off a surface, the angle of incidence is equal to the angle of reflection.

#angle theta=angle theta'#

For a curved mirror as in the figure below

A tangent is drawn at the point of incidence, and normal is drawn to the tangent.

Sebastian Acosta · Answer

undefined We draw a normal between the reflected ray and the incident ray to determine the angle of incidence and the angle of reflection accurately. A normal represents a line perpendicular to the surface at the point of incidence. It serves as a reference line for measuring angles of incidence and reflection.