Telephone and Sound-A basic look

Author: Ayaan,  Learner, Age 11 years.

(This is an assigned project that aimed to walk learners into the basics of sound. This particular write up relates to the part that Ayaan worked on.)

There were three components to this project

  1. Transmitting sound from point A to point B
  2. Measuring Sound
  3. Deconstructing a real telephone to find how it works

Transmitting sound from point A to point B

We used a string telephone for this part of the project. First, we took two paper cups and made two tiny holes in the paper cups. Next we put kite string through the holes. Then we tied knots so that the strings do not come out. We then sent someone down to take the string (tied to one cup) from the person in the balcony. The person down went some distance through an open ground to another balcony where someone was standing. The person threw the string upwards to the person in the balcony who caught the string and tied it to the second cup. The cup and string telephone was now ready.

Problems faced and our solutions

Problem 1

The first problem was the people around us while we were working. They used to work or walk in the way. By doing that, they accidentally broke the string many times and our project.

Solution: We thought, discussed among ourselves and got a solution. We told everyone please do not come in our way between 10 am and 12pm.

Problem 2

The string was coming out of the cups too often

Solution: we thought about it and this time, instead of putting knots, we put a matchstick stick and tied one knot to it.

Measuring Sound

  1. What is Sound? Sound is a form of energy hat travels through waves of vibrating particles
  2. What is decibel? Decibel is a way of measuring sounds
  3. How can we measure sound? We can measure sound using a decibel meter
  4. Do we need to measure sound? In some ways, yes. For example when you play loud music after 11pm. The police will measure the sound and if it is high, you will have to pay a fine. Another example is measurement of sound before a rocket launch. They will use a decibel meter and  tell people that it is dangerous to go near when a rocket launches because it can harm your ears. There are examples where you do not have to measure sound. For example, when you are talking to someone else. Another example is when you are talking on the phone.
  5. What is the range of sound? An average human can hear between 0 decibels to 150 decibels.
  6. What do you measure when you say “measure sound”? We measure the width of the waves to get the volume of the sound.

Deconstructing a wired telephone

The telephone has the following main parts

  1. Microphone that converts the electric waves into sound waves that we can hear it
  2. Mouthpiece that converts sound waves into electric waves
  3. Cables that send the electric waves to the telephone Base.

How does a wired telephone work?

First, you speak into the mouthpiece that turns the sound waves into electric waves. The electric  waves travel through the cable, then through the wire that goes through the wall and joins the telephone wires that reaches the telephone exchange.

If you want it to go abroad, the telephone exchange sends it to the satellite as radio waves and it goes to the telephone exchange of other countries where it is converted back to electric waves. These travel back through the telephone wires to the telephone base and then through the cable. Then, the microphone converts it back into sound waves so we can hear it.

If you are calling within the country, the waves travel through the cable to the telephone base to the exchange and then to the telephone base of the other person, and through the cable to the microphone. The microphone converts the electric waves into sound waves so we can hear. That is how a wired telephone works.


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