Objects can be classified based on their ability to transmit light.

Opaque objects: These do not allow any light to pass through them. As a result, you cannot see through opaque objects at all. Examples include wood, metal, and stone.

Transparent objects: These allow light to pass through them completely, making it possible to see clearly through them. Examples include clear glass and clean water.

Translucent objects: These allow some light to pass through them, but not enough to see through them clearly. Examples include frosted glass and some types of plastic.

Shadows are formed when an opaque object blocks light. When an object is held in sunlight or another source of light, it casts a dark shape on the ground or another surface. This dark area is known as a shadow. The shape of the shadow depends on the shape of the object blocking the light.

To see a shadow clearly, a light source, an opaque object, and a surface (or screen) where the shadow can be cast are required. Shadows can provide some information about the shape of objects, but they can also be misleading. For instance, shadows can appear distorted based on the angle and distance of the light source.

Characteristics of Shadows