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How to Make a Homemade Two-Way Communicator

Sound waves can travel along an object instead of through the air. To demonstrate this principle of sound, make a homemade two-way communicator using string. Supplies from a hobby store or crafts store will be needed, as will tools found around the home. You will not need batteries to power your homemade communicator.

Things You'll Need

2 soup cans
Can opener
2 plastic containers, 2 lids
Dishwashing liquid
Paper towels
Nail. 1/2-inch diameter
Hammer
Cotton string, 25 feet
Assistant

Instructions

- 1
  Remove the labels from the two cans. Stand both cans on a table. Open the top of each can with a can opener and dispose of the lids in the trash. Empty out each can into a plastic container. Put the lids on the containers and place them in the refrigerator.
- 2
  Put a drop of dishwashing liquid into each can. Wash out each can with tap water from the kitchen sink. Dry each can with a paper towel.
- 3
  Place both cans face down on the table. Drive a nail through the top of each can, at the center, with a hammer. Remove the nail.
- 4
  Run an end of the string through the hole in one of the cans. Run the other end of the string through the hole in the other can. Turn both cans over.
- 5
  Tie a double-knot in the ends of the string so that they can not be pulled out of the cans.
- 6
  Have an assistant hold one can while you hold the other. Have the assistant walk away from you until the string is taunt. Place the open end of the can, that is now a two-way communicator against your ear.
- 7
  Have the assistant talk into the open end of the can as you listen to what he is saying. Have the assistant hold the open end of the can against his ear as you speak into the open end of the can to reply to what he has said.

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