STEAM Connections: Prism Power

Why do rainbows form after a rainstorm? Learn how to make rainbows on your own with a few simple materials.

Rainbows are a result of the refraction and reflection of light, both of which help form the color spectrum. Reflection is when light bounces off an object. Refraction is the bending of light as it passes through different mediums.

When light meets a water droplet, it is refracted, or bent, as it passes from the air into the water. After that, it reflects off the inside surface of the water droplet before refracting again.

Check it out and follow along with our video below:

STEAM Connections

In this experiment, we can see for ourselves how water can act as a prism, both refracting and reflecting the water in turn. To record your observations, bring along crayons, colored pencils, or any other method to draw the rainbow!

Supplies

Below is what you will need to conduct this STEAM Connections experiment:

Shallow pan
Water
Small mirror
Sheet of white paper
Sunny window or a flashlight

Instructions

Fill the shallow pan about halfway full with water.
Place the mirror partway into the water at an angle. It should be facing the light.
Shine your flashlight into the water where the mirror is underwater. You can also use sunlight, bring the pan and mirror outside or to a window so the sun can shine on the mirror underwater.
Hold the piece of paper above the mirror. Adjust the angle until you see the rainbow appear.

Review

As you experiment, record your observations:

Did you notice all the colors in the rainbow you created?
How are we able to see so many colors from just one light source?
Was there a color that was bigger than the other colors?
Do the colors always appear in the same order?
From what position did you see the rainbow best?

White light consists all the colors found in the visible spectrum. The visible spectrum is a range of wavelengths that can be seen with the human eye. Each color has its own wavelength on the visible spectrum. When light is bent or refracted, we can see those different colors.

Conduct additional experimentation and see whether your rainbow looks different as you adjust the piece of paper. Does the rainbow get bigger or smaller when you move the paper closer to the water? What about when you move it further away?

Continue Learning

Here are some items and books in the library collection you can check out to learn more! You will need a Plano Public Library card to access these materials.

STEAM Kit: Optics – Lenses & Prisms
Try using real prisms to experiment further with light and rainbows!

I See Rainbows
by Kathryn Beaton

All About Light
by Angela Royston

Manipulating Ligh t: Reflection, Refraction, and Absorption
by Darlene R. Stille

Interested in making more STEAM Connections? Check out our full playlist of STEAM videos, and download activity worksheets to accompany each one!