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STEM Activities

At-Home Edition

Paper Cup Phone


Materials Needed:

  • 2 paper cups

  • 10-20 feet of yarn or string

  • 2 paper clips

  • Sharpened pencil (to pierce the cup with)


How to:

  1. Use the tip of a pencil to poke a small hole at the bottom of each of your two cups.

  2. Thread the string through the hole of one cup. 

  3. Tie a knot in the yarn on the inside of the cup to keep it in place. If the string keeps slipping through the hole, you can tie it to a paper clip to help keep it in place.

  4. Pull the string through the bottom of your second cup, securing it with a knot on the inside.

  5. Keep the string taut when using your cup phones.

  6. When one person whispers in their cup, the other should be able to hear their voice through their own cup.


How does it work?

A simple paper cup phone works by transmitting sound vibrations along a tightly pulled string. The bottom of each cup serves as a combination "microphone" and "speaker," picking up sound vibrations on one and reproducing the sound at the other. Speaking into the cup transmits the sound of the speaker’s voice into the bottom of the cup. As the bottom of the cup vibrates, it transmits the vibrations into the taut string. The sound travels along the string as a longitudinal wave and then vibrates the bottom of the receiving cup. The cup transmits the sound into the air around the listener’s ear, allowing her to hear the speaker.

(From, 2020)

Want to learn more?

Check out these eBooks (available on Hoopla with your library card):

paper cup 1.jpg
paper cup 2.jpg
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