String Telephone

INTRODUCTION

Besides traveling through air, sound can also travel through solid objects.

MATERIALS

• 2 paper or plastic cups (empty yogurt containers work well)
• 1 piece of string about 2 meters long
• Scissors
• 1 pushpin
• 2 paperclips

WHAT TO DO

1. Poke a small hole in the bottom of each cup with the pushpin.
2. Thread the string through the holes and tie a paperclip to each end of the string to ensure that it is secured inside the cup.
3. Give one cup to a friend, and take the cups far apart, so that the string is tight. Talk and listen to each other through the string telephone.

QUESTIONS

1. What happens if the string hangs loose?
2. What happens if you hold the string?
3. What happens if you connect three or four string telephones together?

SUMMARY

When you talk into the cup, you cause it to vibrate. This in turn causes the string to vibrate, which causes the cup on the other end of the string to vibrate. Whoever is listening hears the vibrations caused by your voice after they have traveled through the cups and the string.

SOURCES

"SOUND: Science Activities." Graham Peacock, Wayland Publishers, Ltd.: New York, 1993, p. 20-21.
"Sound Science." Etta Kaner, 1991, Addison-Wesley, New York, p. 88-89.
"Sound." K. L. Siepak, 1994, Carson-Dellosa Publishing Co., p. 31-32.

© S. Olesik, WOW Project, Ohio State University, 2000.