What Is A Shadow?

A shadow is formed when light travels in a straight line. A shadow does not seem to form on a cloudy day. It is a phenomenon that is commonly seen on a clear sunny day. If a person stands with his or her back towards the sun, he or she is sure to see his or her shadow, which appears to be following him. There are times when it appears as if the person is chasing or following his or her shadow.

The shadow of an object is formed when an opaque object or an opaque material is placed in the path of rays of light. The opaque object or material, unlike a transparent object or material, does not let the ray of light pass through it. The light rays go past the edges of the opaque object. This creates the outline of a shadow. The centre of the shadow receives no light at all. It is a dark portion known as the umbra. The lighter part is known as the penumbra. It receives some light from parts of the source of light.