How Colored Shadows Work

This simulation demonstrates both the principle of additive color mixing and how colored shadows are formed.
To understand colored shadows, there are a few important concepts to know.

Each flashlight emits only one color of light: red, green, or blue. These three colors are known as the primary colors of light (RGB).
When inks or pigments are mixed, they become darker. In contrast, when beams of light overlap, they become brighter.
When there are two or more light sources, each shadow is the area where one particular light source is blocked.

For example, a shadow created by a red light is a region where only the red light is missing.
If lights of other colors shine on the object from different directions, the shadow can still receive and reflect those other colors of light.

In conclusion,

The color of a shadow is determined by the combination of the remaining light that reaches the shadow without being blocked by the object.

Examples in Everyday Life

Stage lighting for performances
Studio lighting for photography
LED lighting decorations
Colored lighting in art museums