Science Fair Project Ideas: Create a Rainbow and Conduct 2 Experiments

By Keren Perles

After a light rain, do you love to look for rainbows? These three project ideas are perfect for kids who love rainbows and want to learn more about how they work.

The Basics of Rainbow Science Fair Projects

Because rainbows are relatively rare and hard to plan for, the chances of your finding a sun-made rainbow at the precise time that you’re ready to do your science fair project are low. Therefore, in order to make a science fair project about rainbows, you’ll have to make your own rainbow indoors. First, put some water in a glass jar with a mirror angled in the jar toward the ceiling. Darken the room, and then shine a flashlight on the mirror. It should project a rainbow onto the ceiling. Follow these directions on making a rainbow if you're having trouble. You can then use this base rainbow to try out any of the experiments below.

Changing the Water

Are some types of water more likely to create a rainbow than others? Test out your hypothesis with this project. Try mixing some dirt or food coloring with the water when creating your rainbow, and see whether that affects the rainbow. That will help you figure out whether smog in the air (and therefore in the water droplets) will affect the chances of a rainbow forming. You can also try using more water or less water, and see how the rainbow changes.

Changing the Light Source

Try using different types of light to create the rainbow and see how the rainbow changes. What about using fluorescent light to create a rainbow, or colored bulbs? How does the type of light affect the rainbow? You can also try using a small pinprick of light or a large flashlight, or holding the light at different angles. This last possibility will help you figure out the time of day that a rainbow is most likely to appear – at high noon or while the sun is rising or setting?

These projects are great ways to use the light of a rainbow to learn more about how light works. Can you think of some other ideas? Use the comments section below to add your own ideas.