Rainbow Science Projects

Watch Light Bend

What You Will Need:

• a glass of water
• a pencil

What To Do:

1. Set the glass of water on the table and put the pencil in so that part of it is sticking out above the water.
2. Look at the pencil through the side of the glass.
3. Now look at the pencil from the top of the glass.
4. Now take the pencil out of the water and look at it.

What's Happening?

The pencil looked bent when you looked at it through the side of the glass, but when you looked from above and when you took it out of the water, of course it wasn't really bent! When light passes through the glass and water, it refracts, or bends. Since the light is being bent in different directions by the glass and the water, it hits your eye from different angles than normal and makes the pencil look bent! (The same thing happens when you dangle your legs into a swimming pool.) It also makes the pencil look bigger than it really is. As the light passes through the water, it bends in odd directions and magnifies the part of the pencil that is in the water. The more water between you and the pencil, the bigger the pencil will look. Try holding it right up to the side of the glass nearest you, and then move it to the other side and watch it grow!

Make A Prism

Most of the time light looks white, but it is actually made up of colors:  red, orange, yellow, green, blue, indigo, and violet. Those seven colors are the same ones you see in a rainbow! A prism is usually made of glass and is used to separate light into its colors. In this project, you can make your own prism to show the colors of light.

What You Will Need:

• a clear glass
• water
• 2 sheets of white paper or cardstock
• a chair
• flashlight (one with a small beam works best)

What To Do:

1. Fill the glass a little more than half-way full.
2. Set the glass on the edge of the chair so that nearly half of the bottom of the glass hangs over the edge. The glass might be a little wobbly, so be careful not to let it fall.
3. Lay both sheets of paper side by side on the floor next to the chair where the glass is.
4. Turn on the flashlight and hold it near the outside of the glass at the level of the water, pointing towards the paper on the floor. 
5. Look for a rainbow pattern to appear on the white paper. You might need to adjust where you are shining the flashlight or where your paper is at in order to see the rainbow clearly. Depending on the shape of your glass and how much water is in it, you might see more than one rainbow. You could also try this by putting the glass of water in a window where sunlight will shine through it instead of using a flashlight.

What's Happening?

When the beam of light from your flashlight hits the outside of the glass, it bends slightly and breaks into its seven different colors. This bending is called refraction. The beam of light is separated into its different colors because each color bends at a slightly different angle. When the light comes out the other side of the glass, it is no longer a beam of white light. Instead, you see all the colors that make up white light in a rainbow shape on the white paper! This setup is a type of prism. A normal prism is a triangular piece of glass, but it works in the same way as the prism you just made.

A prism refracts light in almost the same way that raindrops refract sunlight to make a rainbow.  The seven colors of the rainbow are called the visible colors of light. White light is made up of all of those colors, our eyes just can't see them until they are separated by water, glass, or something else. There are more colors of light, but our eyes can't detect them. Another way to see the rainbow colors of white light is to hold the back of a cd up to a light bulb. To see the colors even more clearly, poke a small hole in a piece of foil and cover a flashlight with the foil so the hole is in the middle, then shine it at the cd.

Make a Rainbow

What You Will Need:

• a garden hose (connected to a faucet outside)
• a sunny day
• permission to go outside and use the hose

What To Do:

1. Get the hose and turn the faucet on.
2. Stand in a spot where the sun is behind you, shining on your back. (You will be able to see your shadow in front of you when the sun is behind you.)
3. Put your thumb over part of the nozzle of the hose so that the water creates a spray when it comes out.
4. Hold the hose out in front of you and turn slowly. Keep you finger over the hose to make a spray. Watch for a rainbow to appear above the water.

What's Happening?

A rainbow should appear just above the spray of water from your hose when sunlight hits the water at the right angle. The water from the hose does the same things that rain does to make a real rainbow in the sky - it refracts the beams of sunlight so that they separate into their different colors. You can see the colors in the rainbow that appears above the water. The rainbow you made is much smaller than one you would see in the sky. Do you know why? It's because the water from your hose is only spraying in a small area. If there were more drops of water for the sunlight to hit, you would see a larger rainbow.

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