How to make an String Telephone

Make a string telephone

What you’ll need?

• 2 paper cups
• A sharp pencil to help poke holes
• String.

Instruction:

1. Cut a long piece of string
2. Poke a small hole in the bottom of each cup
3. Thread the string through each cup and the knots at each  end to stop it pulling through the cup
4. Move into position with you and a friend holding the cups at a distance that makes the string tight
5. One person talks into the cup while the other puts the cup to their ear and listens

What’s happening?

Speaking into the cup creates sound waves which are converted into vibrations at the bottom of the cup. The vibration travel along the string and are converted back into sound waves at the other end so your friend can hear what you said. Sound travels through the air but it travels even better through solids such as your cup and string, allowing you to hear sounds that might be too far away when travelling through the air.