Underwater telephone

Underwater telephone

Underwater telephone

Follow FizzicsEd 150 Science Experiments:

You will need:

Two plastic funnels

Rubber tubing to fit the funnels

One balloon

A friend in a pool

Adult supervision

Underwater telephone science experiment - materials needed
1 Underwater telephone science experiment - cutting the balloon

Fir both ends of the rubber tube with the funnels.

2 Underwater telephone science experiment - balloon stretched over small funnel

Stretch the balloons over the end of one of the funnels, making sure that it is tight across the funnels opening.

3 Underwater telephone science experiment - funnel underwater

Place the funnel, with a balloon, into the pool.

4 Underwater telephone science experiment - holding the telephone

Place the other funnel over your ear. Can you hears sounds from inside the pool?

5 Underwater telephone science experiment - holding the telephone

Have a friend talk to you from under the water. Can you hear them clearly?

Why Does This Happen?

Sound is produced by vibrations. The stretched balloon picks up vibrations travelling through the water. As the balloon starts to vibrate it amplifies the sound so you can hear.

Whales can send and receive messages through water many kilometres away due to sound being able to travel faster through water than it does in air. Why is this so? Liquid molecules are packed more tightly than the gas molecule. This means that the vibrations travels faster through liquids than it does through air, and with less energy loss.

Learn more!

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