How to make telephone with cup: A simple cup phone works by transmitting sound vibrations along a tightly-pulled thread. The telephone work in a very simple way. Sound waves cause the bottom of the first cup to vibrate. This vibration, in turn, cause the thread to vibrate. The vibrating thread causes the bottom of the other cup and the air inside to vibrate. The sound the student hear are a result of these vibration; the air in the second cups strikes their eardrums in nearly the same way it struck the bottom of the first cup as their partner spoke into them.
- Two paper cup
- Cotton thread about 4 m (4 yds.)long
- Use the toothpick or your pencil to punch a small hole in the center of the bottom of each cup.
- Push one end of the thread through the hole of each cup.
- Break the toothpick in half and tie each end of the thread to one piece of toothpick so the thread cannot pull out of the hole in the cup.
- Keep the thread tight and be sure it doesn’t tough anything.
- Put the cup to your ear and have your friend talk into his or her cup. Now you talk and have your friend listen.
For critical thinker :Make a “party line” by crossing the line from two set of telephone over each other. Three people can then listen while one person talks. See if you can include a third set of telephones.