Make a great set of musical bottles with this experiment. You can even play a song with them too. Franklin invented a musical instrument called a Glass Armonica (or Glass Harmonica, hydrocrystalophone, or simply Armonica), based on this principle. He mounted glass cylinders on an axle which rotated through a trough of water. Both Beethoven and Mozart composed pieces for it.
You'll need these materials to make the bottle pipes:
8 (or fewer) identical glass soda bottles
A pitcher of tap water
- Place all of the bottles in a straight row. Pour a small amount of water in the first bottle, a moderate amount in the second bottle, and a larger amount in the third bottle. Continue filling each bottle with more and more water till you run out of bottles to fill up.
- Blow across the tops of the bottles. Don't blow into the bottles, just blow across the openings on the top. This may take a little practice, ask an adult for help if you need it.
- You can add or pour out water to change the tone of each bottle. Maybe you can create a scale, or a song.
- Now try hitting the bottles with a spoon. Do you hear a different noise from each bottle? Why is this happening?
The bottles produce a sound because the air vibrates inside the bottle when you blow across it. The more air that is in the bottle, the lower the sound of the bottle is. The bottles with more water produce a higher sound because there is less air vibrating inside the bottle. The water affects how much air is inside each bottle.
Fun with Franklin is a great opportunity to learn and have fun, but if you are conducting an experiment you should be careful. Although the experiments on Fun with Franklin are relatively safe, you should make sure to do the following:
Follow all directions carefully and work in a clean, safe area.
Tell your parents/teachers you are conducting an experiment and ask if they want to help.
If you have questions or problems, feel free to ask an adult for help.
Don't do any experiment that you feel is too complex.