Book 13, Question 45
Why Can’t You Make Black by Mixing Colored Lights?
When you mix colored lights, every new light adds more brightness. So the mix gets lighter, not darker. Black is the absence of light, so adding lights can never make it!
More fun facts
- Projectors cannot project black, because black is really the absence of light.
- The black parts of a projected picture are actually a very dim white, which looks black next to much brighter areas.
- In a projected checkerboard, the black squares are really brighter than the wall outside the picture.
- Our eyes and brains judge a color by comparing it with the colors around it, not by measuring the light exactly.
- Mixing paints or filters works the opposite way: yellow, magenta and cyan filters together subtract all the light and leave black.
Sources: Wtamu, animations.physics.unsw.edu.au
Questions kids ask
How do movie theaters show black?
They send very little light to those spots, and your brain reads the dim areas as black.
Can filters make black even if lights cannot?
Yes. Stacking yellow, magenta and cyan filters blocks the light and leaves black.