Sept. 3, 2003

The Spoon That Thinks It's a Bell

How can a spoon act like a bell? Read on and find out.

You'll need:

• a teaspoon
• 4 feet (1.2 meters) of string
• scissors
• a soup spoon
• a table or chair
• a serving spoon

What to do:

• Cut a piece of ordinary string about four feet (1.2 meters) long. Tie a simple sliding loop in the middle of the string. Do this by simply wrapping one end of the string over the other and pulling the open loop down so that it is halfway between the ends of the string.
• Don't tighten the loop into a knot. Leave it open about half an inch like this:

• Slip the handle of a teaspoon through the loop and tighten the loop so the spoon won't slip out. Adjust the spoon so it hangs with the scoop end just a little lower than the handle.
• Now press one end of the string against the outside of your right ear and the other string end against the outside of your left ear. Don't put the string into your ear.
• Next, swing the string gently so that the scoop of the spoon hits the edge of a table or the back of a chair. Listen to the sound you hear.

What's happening?

By swinging the spoon gently you will hear a sound that is nothing like a spoon striking a table. It's more like a bell. In fact, it's like a church bell.

Why?

The string conducts the vibration of the spoon. Not only does string carry sound waves better than air, it directs them right into your ear. This accounts for the deep bell-like tone you hear.

What now?

Repeat the experiment using a soup spoon and listen to the deeper tone it creates.

Then, give your ears a treat, and do it with a serving spoon. Because of its greater size its sound is much deeper.

Reprinted with permission of Sterling Publishing Co., Inc., from Amazing Science Experiments with Everyday Materials by E. Richard Churchill and illustrated by Frances Zweifel. Text © 1991 by E. Richard Churchill. Illustrations © 1991 by Sterling Publishing Co., Inc.

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