Splitting White Light into a Spectrum

It's been awhile since we talked about rainbows, but this simple little activity was a great refresher. Using simple household items, my sons and I split white light into a truly impressive spectrum of colors.

What You Need 1 used music or computer CD Aluminum foil Working flashlight Rubber band Pushpin Dark room
Prep Tear a small piece of foil and cover the flashlight with it. Secure it in place with the rubberband. Using the pushpin, puncture the center of the foil so it has a tiny hole.

Split the Light Now turn the flashlight on, grab the CD and head into a dark room (we were in the laundry room). Shine the flashlight at the back of the CD, adjusting the angle until you see a straight column of rainbow light.

This stripe of vivid color is the flashlight's spectrum.

How it Works The tiny groves in the CD when it's laser recorded act as a diffraction grating that split the light.
My boys were so impressed to see their own tiny rainbow! This great activity came from the book Beyond the Solar System.