Optics
Colored Shadows
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Shadows need not always be black. When red, green and blue lights shine from different directions, an object can block one light while the others still reach the screen. The remaining lights mix to make colored shadows.
These shadow colors are the complementary colors of the blocked light:
- block red → you see cyan
- block green → you see magenta
- block blue → you see yellow
Where all three lights are blocked, the shadow is dark. Where all three lights overlap, they make nearly white light.
Place different objects in front of the lights, or make funny shapes with your hands. Move them around and watch the colored shadows separate, overlap and change.