Waves in a Bottle

Kids should not attempt this project without adult supervision.

Background Information

Surf's Up!


This project illustrates many of the principles of wave motion in the ocean. It also makes a really cool decoration for your room. Try adding sea shells or plastic fishes to your miniature ocean for fun!

What you will need:

1. Safety goggles for working with paint thinner

2. Green and blue vegetable dye

3. A quart or larger container with a tight lid (a 2-liter bottle should work)

4. Water

5. Paint thinner or turpentine available at Home Depot or Home Base.

6. Duct tape or other strong waterproof tape

The Set-Up

1. Put on safety goggles and don't smoke when handling paint thinner.

2. Fill the bottle half way with water.

3. Add green and blue dye to make it look like the ocean.

4. Fill the bottle all the way to the top with paint thinner.

5. Tightly seal the bottle with the cap and wrap it with duct tape to keep it from leaking.

6. Put the bottle on its side, stabilizing it so it doesn't roll.

Things to Try

1. Tap the end of the bottle lightly with your finger. What do you see. Try estimating the wavelength of the waves. The wavelength is the horizontal distance between two successive crests.

2. Repeat the experiment tapping in different places. Does it make a difference where you tap the bottle? Describe and explain the differences that you see.

3. Gently lift one end of the bottle then let it down. What do you see now?

4. Repeat the experiment a few times lifting the bottle higher and higher each time. Does it make a difference how high you life it?

5. Rock the bottle back and forth. Steadily increase the magnitude (strength) of your rocking. What happens to the waves? Is there some point at which all wave motion becomes chaotic?  Why?

Thought Questions:

1. Why do the water and mineral spirits separate from each other? Which one is one top? Which one has the greater density?

2. What is the disturbing force in each of the experiments? What is the restoring force?

3. What is the difference between the internal waves in the bottle and wind-driven waves on a beach?