You will need
- wire coathanger
- cotton thread
What to do
Tie a 50 cm length of cotton thread on each end of a wire coathanger. Wrap the other end of each thread around your forefingers. Bend over so the coathanger can swing freely and bump it against a wall or chair.
What do you hear?
Try it again, but this time with your forefingers in your ears! Try bumping it against different objects. Bend the coathanger into various shapes. Does this make any difference to the sound you hear?
When you bump the coathanger, it shakes or vibrates, making a noise. The noise is louder when your fingers are in your ears because the vibrations travel better through the tight cotton threads than through the air.
Next time you're in the bath, put one ear under the water while tapping a spoon on the side of the bath. Notice how much better the tapping noise travels through the water.
From: Science Toys and Activities, published by Questacon – The National Science and Technology Centre.