The following are alternative methods to demonstrate the separation of white light into the color spectrum. On a bright sunny day, students can go outside and use sunlight through a prism to project a color spectrum on a piece of white paper. Cut a slit 1 cm wide and 15 cm long in a piece of black construction paper. Place the paper over the glass of an overhead projector so that just a slit of light is projected in a darkened room. Have students position a prism close to the projector, within the light beam, and experiment to find the most optimal placement for projecting a color spectrum.
Students can spray a fine mist of water in bright sunlight to produce a rainbow.
This is an excellent rainbow demonstration since, as with natural rainbows, water droplets are used. Or, this can also be done in the classroom using an overhead projector projecting a slit of light. Spray a fine mist in front of the projector across the light beam. A color spectrum can be seen within the mist. Play recordings of songs about rainbows such as Somewhere Over the Rainbow or The Rainbow Connection .