Exploring the Spectrum Glass prisms and water droplets create rainbows by bending different wavelengths of light by different amounts. Rainbows can also be made using a diffraction grating. A diffraction grating has between 15,000 and 30,000 tiny lines etched into every inch of the plastic film. When light passes through the diffraction film, it forms little light sources between each line. These light sources interfere with each other.
Different wavelengths combine in slightly different directions producing a rainbow spectrum.
Different sources of light produce different spectra. Using a diffraction grating, observe the spectrum of each type of light and then draw the spectrum with colored pencils. Show differences you find. Compare the flashlight with the two light bulbs. The fluorescent tube and street lights contain glowing gases.