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Looking for a fun and easy at-home science project to do with your curious little one? Try creating a cup phone! This easy STEM activity for kids, helps children discover the fun science behind the cup phone and experiment with how using different string materials and string lengths might affect the quality of sound / sound waves!
The science behind the cup phones
Just like with Alexander Graham Bell’s early telephone, the cup phone uses vibrations to help with communication. When you talk into one of the cups, the sound waves from your voice make vibrations on the bottom of the cup. The vibrations travel along the string, just like the vibrations traveled along the wire in Bell’s phone. When the vibrations reach the other cup, they turn back into sound waves and your friend can hear what you said.
Think about what happened when you let the string droop in between the cups. Was it easier or harder to hear your friend’s voice? Why do you think that is the case? If the vibrations need to travel along the string to turn back into sound waves, why did the drooping string make it harder to hear your friend’s voice?
- You will be making cup phones. Use the pushpin to poke holes in the bottom of the cups and tie them together with a piece of string. Try making several different phone designs by changing:
- The type of cup used (but use the same type of cup on an individual phone)
- The type of string
- The length of string
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Hold one cup and have a friend hold the other cup. Take turns talking into one cup while the other person listens into the other. Try whispering so that you know you are hearing their voice come through the phone.
- Which phone has the clearest sound?
- Which phone has the clearest sound?
- Does the length of string affect how well your telephone works? • What helps the telephone work better – if the string is pulled tight, barely straight, or with lots of slack?
Think about what happened when you let the string droop in between the cups. Was it easier or harder to hear your friend’s voice? Why do you think that is the case? If the vibrations need to travel along the string to turn back into sound waves, why did the drooping string make it harder to hear your friend’s voice?
- Which phone has the clearest sound?
- Does the length of string affect how well your telephone works?
- What helps the telephone work better – if the string is pulled tight, barely straight, or with lots of slack?
Click here to download the PDF to explore the Cup Phone Exploration Activity!
