Almost all surfaces reflect light. The sensor cells of our eyes sense this light and process the visual information. The flatter and whiter the surface is, the more light it reflects. For example, a mirror reflects light well because its surface is extremely flat and has a metallic white color.

There are different kinds of mirrors. Some mirrors magnify the objects in the mirror, whereas other mirrors reduce the size of the objects in it. These phenomena can be influenced by changing the shape of the mirror.

Concave mirrors magnify the objects reflected by it. For example, a pot lid can act as a concave mirror. Concave mirrors are used in telescopes and binoculars. They are also used when applying makeup or shaving.

When a pot lid is turned upside down, the result is a convex mirror. Convex mirrors reduce the size of the objects reflected in it. They are used in dangerous crossings and in cars.