How Do Reflections Form

When you look in a mirror, you see a clear reflection of yourself. The picture you see in a mirror is called an image.

Bouncing Light

Mirrors reflect light. Why do you see a clear image in a mirror but not in a sheet of paper?

A sheet of paper has a rough surface. When rays of light strike the paper, they are scattered in all directions. A mirror has a very flat, smooth surface. Rays of light bounce off a mirror without being scattered.

Predicting the path of the light

If you shine a ray of light at a mirror, it reflects off the mirror. The law of reflection tells us about the direction in which the ray is reflected. The diagram below shows this.

Here is how to understand this diagram:

• The mirror is represented by a straight line; the shading shows the back of the mirror.
• The ray of light coming in is called the incident ray.
• The ray of light going out is the reflected ray.

To predict the direction of the reflected ray, we need to draw the normal to the surface of the mirror. The normal is a straight line drawn at right angles (90 degree) to the mirror at the point where the ray is reflected.

The law of reflection of light says that the two angles marked in the diagram are equal. (Note that each of the angle is measured from the normal to the ray, not from the ray to mirror.)