Tin Can Telephone

Do you get in trouble for spending to much time talking to friends on the telephone? Here is a fun way to find out how sound travels and talk to friends at the same time.

What You Need

1. An adult to help
2. Two metal cans, clean and dry (Be sure that there are no sharp edges)
3. Ten to Twelve feet of a piece of small diameter string such as kite string or nylon string

What You Do

1. Make a 'Tin Can Telephone' by punching a small hole in the bottom of each can. Each hole should be just large enough so that the string will go through.
2. From the outside, insert one end of the string into the hole in one can. Tie a couple of knots in the end of the string so that it will not slip back through when pulled tight. Do the same with the other end of the string using the other can.
3. With one person holding each can, stretch the string so that it is tight. One person talking into one can sends vibrations through the tightened string to the other can. The person with their ear to the other can will be able to hear what was said.

Why it Works

When someone speaks or makes a sound, the air ripples or vibrates. The word 'vibrate' means to move up and down, or back and forth rapidly. Our ears collect the sound vibration, or sound waves and send them to our brains. Then we hear the sound.

When you pull the string tight and talk into one of the cans of your tin can telephone, the sound vibrates across the taut string to the other can. The person at the other end of the telephone hears your message after his or her ears collect the sound vibrations and send them to the brain to be processed.