Try this at home too!
By filling juice bottles with different amounts of water, you can
create some catchy tunes! Here's how to do it with real bottles at home: take six
glass juice bottles or very tall drinking glasses and fill them with different heights
of water to make a six note scale. (Use your voice or a piano to see if you're in
tune!) Number your bottles, starting with the one holding the most water, so they
look like the ones above.
If you use Snapple bottles, you can fill your bottles to these heights:
|
5 1/2 "
|
4 "
|
3 1/4 "
|
3 "
|
2 1/4 "
|
2 "
|
|
1
|
2
|
3
|
4
|
5
|
6
|
Try composing your own songs. Add two more juice bottles to your collection and you'll
be able to make a whole octave!
| Q: Why do the different
amounts of water in the bottles create different notes when the bottles are tapped? |
Tapping the bottles with the stick causes the glass of the bottle to vibrate and
produce sound. The water dampens these vibrations. So, the less water in the bottle,
the faster the bottle vibrates and the higher the pitch.
Check this out!
Instead of tapping your bottles, blow into them.
Q: Notice anything
different? |
The effect is the exact opposite! The bottles with the most
water in them make the highest notes. This is because you are now making
the air (not the glass) vibrate. Shorter columns of air will have a higher pitch
when you blow, just as shorter columns of water have a higher pitch when you tap
them. The bottles with the shorter air columns are the ones with the most water in
them.
Here's another bottle trick to try
Do this one with a friend and two bottles. Hold one bottle with the
opening close to your ear. Have your friend blow into the other bottle until it produces
a sound.
Q: Do you hear
your bottle humming too? What's going on? |
Your friend's bottle made vibrations that travelled through the air
to your bottle making it vibrate. Your bottle vibrated just like your friends's bottle,
so it sounded just the same. They were in harmony. This special exchange of vibrations
is called resonance.
Try putting water in your friend's bottle to change the pitch of the
sound.
Q: Does your bottle
change pitch too? |
|
