Science Unit 6a Page 4

• The lighter shadow surrounding the darker shadow is called penumbra, where reflected light reaches, making it look grey
• The size and shape of shadows can vary, changing in shape and size
• A large source of light creates a shadow that is dark in the centre and lighter at the edges, usually casting a shadow with an umbra and a penumbra
• Light intensity varies between sources, with electric bulbs having greater intensity than candles
• A small source of light, like a torch, casts a very dark shadow with sharp edges
• At midday when the Sun is overhead, shadows are short; in the morning and evening when the Sun is low, shadows are long
• When light falls on an object, a shadow can be seen on the surface directly behind the object, appearing larger when the surface is further away
• Shadows can provide information about the time of day
• Shadow brightness (or darkness)

  The amount of light that is blocked by the object, with a darker shadow indicating that more light is being blocked and a lighter shadow indicating that less light is being blocked. The size and brightness of a shadow are not directly related.
• Shadow size


  The area covered by a shadow, which depends on the position and distance of the light source and the object blocking the light. A larger shadow indicates that the light rays are spreading out more before they reach the surface.