Create a Color!

Some weeks ago, we talked about how white light is composed of all the colors of the rainbow. You can use a prism to separate white light into red, orange, yellow, green, blue, indigo, and violet. If you had a way of combining the colors again, you'd recreate the white light.

Have you ever tried mixing paints or food coloring to get different colors? You can combine red and yellow to make orange, blue and red to make purple, and blue and yellow to make green. But what if you mix all the colors together? If the paints acted like light, you would make white paint! But that isn't what happens at all (try this if you haven't already). In fact, you get a yucky grayish-black color. So why do the paints act different from light?

Remember that we talked about why objects appear to be different colors - they absorb all the waves except those that create the color you see. The same thing happens with paint. When you mix them all together, they end up absorbing almost all the waves, and that makes the paint mixture appear grayish-black. This is called subtractive mixing because waves keep being removed when colors are blended.

The colors in light behave different. They mix in an additive way. Red light only has waves that appear red, and blue light, waves that look blue. When you mix them together, you get waves that look pinkish-purple (a color called magenta). Not surprisingly, blue and green make a sort of turquoise (cyan). But when you mix red and green, you don't get some ugly brownish color - you get yellow!



Yellow??!!?? This is hard to believe. You can actually play with additive color on your computer. Open up a program that lets you mix your own colors. For example, you computer probably has a program called Paint or MacPaint. You may need someone who can use this program to help with this (you can do the same thing in Word or PowerPoint). Draw a square or other shape, fill it with the paint bucket tool, then find a way to create "Custom Colors". You'll see boxes labeled "Red", "Blue", and "Green". Put various numbers in to see what result you get. You can also adjust how light or dark the color is. Can you invent a new color? What will you call it?