The String Telephone

Did you know that you can build your own “telephone” with some plastic cups, some string, and a couple of paper clips? It’s true! Of course, you’ll need a little science too!

Here’s What You Need

• Two plastic cups
• String or twine
• Paper clips
• Pencil or nail (for poking holes)

Here’s What You Do

Ask your adult assistant for help with this part. Use the pencil or nail to poke a small hole in the bottom of each plastic cup. Thread the string or twine through the hole in the bottom of each of the cups. Tie the paper clips to the ends of the string. The paper clips should be inside the cup. They will keep the string from slipping through the hole.

Now it’s time to make a call! Hold one cup in your hand and give the second to your student assistant or friend. Pull the cups so that the string is tight. Make sure the string is nice and tight. Now, talk into your cup while the other person holds the cup to his/her ear. Experiment with your phone. How long can you make the string and still hear your friend? Does the phone sound different if you use empty soup cans instead of plastic cups? What about using two different sized cups? There are lots of great experiments you can do with your phone.

The Science Behind The Phone

Sound travels through things as a wave. When you talk into the plastic cup, the sound waves cause the bottom of the cup to move back and forth very fast (about 1,000 times a second). Scientists call this fast, back-and-forth movement vibration. The vibrations in the bottom of the cup cause the string to vibrate. The string then causes the bottom of the second cup to vibrate like the bottom of the first cup, producing sound waves. The second person can hear the sound waves and can therefore hear what the first person says.

Wondershop Fast Fact

Here are some interesting things you might not know about the telephone:

• Heinz Ketchup was invented the same year Alexander Graham Bell made his first phone call.
• Alexander Graham Bell thought the phone should be answered with “Hoy, Hoy” instead of “Hello”.
• By 1910, New York Telephone had 6,000 women telephone operators.
• Mark Twain was one of the first to have a phone in his home.
• There was no technology for timing calls in the early days of telephones, so the phone company used to charge a flat monthly rate for service.
• In 1910 the train fare from New York to Philadelphia was $4.50. A phone call between the same two cities was 80 cents.
• As a tribute to Alexander Graham Bell when he died in 1922, all the telephones stopped ringing for one full minute.
• From one telephone in 1876, the count grew to 11,000,000 (million) telephones nationwide by 1915.
• In 1956 the first transatlantic telephone cable was placed on the ocean floor and rests as deep as 12,000 feet! It runs from Newfoundland, Canada to Scotland!
• There are 149,084,370 telephone lines in the world and thousands more are being added every day.

Source: www.chevroncars.com/learn/odds-ends/telephone-facts