Filtering Light

Everyone likes colored lights. You put them on your tree at Christmas, unless you prefer white lights. Those exit signs in theaters and public places are orange. The lights on emergency vehicles are different colors, too. But the thing is, light is white, for the most part. So how do we get all these different colors?

To get different colors of light, we put our lights in colored tubes, or filters. Only certain colors can actually get through the glass, though, and that is why we have different colors. Some of the colors pass through, the rest are absorbed by the filter. The color we see, however, not only depends on the filter, but what the light is shining on.

If you put a red ball under a white light, you will see a red ball. If you put it under a red light, you will see a red ball. The red will probably be a slightly different shade, but it will still be red. Now, imagine if you put the same red ball under a green light. It will look like rather Christmasy, right? Wrong. The ball will be black. You see, the red ball absorbs the green light, so instead of looking like a really weird Christmas ornament, it rejects the black light, and that's what we see.

Here's one last interesting thing about light. The lights you have in your house produce more yellowish white light than the ones in stores. The lights in stores are usually fluoresent lights. This means that whatever is under the store lights looks a little different than in your house. This is a problem at paint stores, since not a lot of people realize that the sample they like looks different in their house!