How do rainbows work?

Find Out!

Have you ever wondered how a rainbow works? You've probably seen one of those colorful arches up in the sky after it rains. Have you ever wondered why they sometimes appear and sometimes don't appear?

During and after a rain shower, the atmosphere is filled with water droplets. In order for a rainbow to be seen, the sun has to be right behind you. When light passes through those water droplets, the light is leaving one medium and entering another. This causes the light to change its direction and bend, which is a process called refraction.

When the light is refracted in the water droplets, the light is split into seven different colors. The colors are red, orange, yellow, green, blue, indigo, and violet. They are always in that order. One way to remember the colors and the order is by remembering the name ROY G. BIV. Each letter in the name is the first letter in each color of the rainbow.

The refraction that occurs in the water droplets to form rainbows also occurs in other places too. When light passes through a prism, the colors that are in rainbows are projected onto the wall (or whatever surface is near). Rainbows can also be seen in bubbles. The light passing through a bubble is refracted through the outer wall of the bubble and reflected onto the inside wall of the bubble.

Try it Out!

1. Let's explore refraction! Fill a glass about halfway with water. Then place a pencil in the glass of water and hold your head at eye-level with the glass. Can you see how the pencil looks broken at the top of the water? This is because the light is bending as it passes from the air to the water.
2. Let's make a rainbow! Get a piece of paper and some markers, crayons, or colored pencils and draw a rainbow. Make sure that you use the right colors and put the colors in the right order on the rainbow! You can also get even more creative and make a rainbow by gluing different colored yarn or any other material on the paper. Just don't forget ROY G. BIV!
3. Now let's look at rainbows in other places! Create your own bubble solution by combining 6 cups of water, 1 cup of Joy dishwashing liquid, and 1/4 cup of corn syrup. Use bubble wands to dip into the solution and then either blow or wave them through the air to create bubbles. Now look at the rainbows that form inside the bubbles because of refraction. (This works best outside on a bright sunny day!)