sciencegeekgirl: Physics Toys Tuesday: Colored shadows

Color subtraction is what happens when you mix together pigments. Red pigment absorbs all light but red (which is reflected to your eye). Blue pigment absorbs all light but blue. So mix red and blue and you’ve subtracted all colors, getting black.

Light’s weird, though. You mix together all colors of light and you get white. The primary colors of light are red, green, and blue. You have receptors in your eyes for each of those colors. If your eye senses both red and green light at the same place, your brain says “cyan” (sort of blue-green).