cbse-class8-physics-2015-->View question View all questions Download question set Listen to this question

Fix a white sheet of stiff paper on a drawing board or a table. Let the sheet project a little beyond the edge of the table. Take a comb and close all its openings except one in the middle with the help of a black paper. Hold the comb perpendicular to the sheet of paper. Throw light from a torch through the opening of the comb from one side so that a ray of light can be seen along the paper on the other side of the comb. Place a strip of plane mirror in the path of the light ray. This ray of light striking the mirror is called the incident ray. After striking the mirror, the ray of light is reflected in another direction. This is called the reflected ray.

Now, cut the projecting portion of the sheet in the middle. Look at the reflected ray. Make sure that the reflected ray extends to the projected portion of the paper. Bend that part of the projected portion on which the reflected ray falls. The reflected ray that fell along this part can no longer be seen.

This shows that the incident ray, the reflected ray and the normal at the point of incidence lie in the same plane.
Listen to this answer