How to draw a normal to the ray?

Hint:When light travels through one material and bounces off a different material then the reflection occurs. If a ray of light is incident on a reflecting surface at a certain point. when a line is drawn perpendicularly to the reflecting surface at the point of incidence, this line is represented as normal. It is an imaginary line incident at \[{90^ \circ }\] to the reflecting surface.

Complete step by step answer:
The reflected light travels in a straight line but in a different direction. The light is reflected at the same angle as the ray hits the surface. The angle of incidence is equal to the angle of reflection. And the imaginary line perpendicular to the surface at the point of incidence is known as normal.

As the above figure is shown \[{\theta _1}\] is the angle of incidence and angle of reflection (as we know both are equal to each other) and \[{\theta _2}\] is the angle of reflection. And the normal drawn perpendicularly on the smooth surface through the point O. For the refractive ray normal can be drawn on the surface at the point of incidence too.

Note:If the light reflects on a smooth surface, all of the light will be reflected in the same direction which is called specular reflection. Along the smooth surface, the normal will always point the same way. If the light reflects on a rough surface the normal will be different along the rough surface which will cause the reflected light to go in different directions. Which is known as diffuse reflection.