Fun demonstration to show show the additive mixture of light. Three primary colored lights are aimed at the same spot will appear as white light, but when an object blocks one or more of the lights different colored shadows appear behind the object. The addition of red green and blue light will yield 8 distinct colors. Black, white, red , green, blue, and the secondary colors of cyan, yellow and magenta. Other colors used as the light sources will yield other shades, depending on what are the initial colors.