What is the condition for shadow formation?
Shadows are formed when an opaque object comes in the path of light
A shadow is formed, when light is blocked by an opaque or translucent object. Opaque objects, such as a tree, completely block light and form a dark shadow. Translucent materials, such as tissue paper, allow partial light through, creates a faint shadow. Transparent objects, such as glass, do not create a shadow because the light passes through them completely.