Introduction Use an overhead projector to project an image of a slit on a screen.
A compact disk can be used as a diffraction grating to spread the white light passing through the slit into a spectrum from red through green to blue. Material An overhead projector and white screen. A piece of cardboard large enough to mount the compact disk at a 45 degree angle in front of the overhead projector, plus some sticky tape. Thin opaque cardboard, large enough to cover the overhead projector. I use manilla folders.