Mechanics of the Telephone

Instructor: David Wood

David has taught Honors Physics, AP Physics, IB Physics and general science courses. He has a Masters in Education, and a Bachelors in Physics.

Learn about the parts of a basic telephone, and how they work: microphones, earpieces, switches, and wires. See how much you've learned, and take a quiz at the end of this lesson.

What is a Telephone?

The phone rings, and you answer it without a thought. It's your grandma, and you have a nice conversation about knitting. But do you ever stop to think about how you're able to do that at all? When the first audio recording was made, people thought it was magic and were scared. Yet talking long distances seems perfectly normal to us these days. Today we're going to address that, and learn how a basic telephone works.

A telephone is a system that turns sound waves into electrical signals so that sound can be transmitted over long distances. Telephones are used to transmit voice conversations, allowing people to talk to each other when they're not all in the same place. Telephone conversations can be between two people, which is the most common case, or between multiple people at once. The telephone was invented in 1876 by Alexander Graham Bell.


How Do Telephones Work?

Basic, old-fashioned telephones are very simple devices. They only contain a few parts: a microphone, an earpiece, a switch in the base of the phone, and wires.

When you speak into a phone, you're actually speaking into a microphone. A microphone contains a magnet mounted on a moving surface that vibrates with the sounds that you project into it. When you speak into the microphone, the magnet vibrates back and forth. When a magnet moves near an electrical wire, electricity is created in that wire.

So when you talk into the microphone, signals that match the vibration created by a voice are sent down the electrical wire. Then, when those signals are sent to another person's earpiece, which is really just a microphone in reverse, they cause the magnet to move up and down in the same pattern. The earpiece is connected to a diaphragm that also moves up and down, re-creating the sound and allowing the listener to hear what the speaker has said.

The microphone can get more complicated, but the basics are the same.
The microphone can get more complicated, but the basics are the same.

Phones also contain switches, which connect you and disconnect you from the telephone line, so sound isn't always being received by the phone. And they do, of course, contain wires, too, because this is how the signal is transmitted all the way to the other person's phone; phones also require exchanges with systems that can make sense of the phone numbers you input, and connect you to the correct place.

To unlock this lesson you must be a Member.
Create your account

Register to view this lesson

Are you a student or a teacher?

Unlock Your Education

See for yourself why 30 million people use

Become a member and start learning now.
Become a Member  Back
What teachers are saying about
Try it risk-free for 30 days

Earning College Credit

Did you know… We have over 200 college courses that prepare you to earn credit by exam that is accepted by over 1,500 colleges and universities. You can test out of the first two years of college and save thousands off your degree. Anyone can earn credit-by-exam regardless of age or education level.

To learn more, visit our Earning Credit Page

Transferring credit to the school of your choice

Not sure what college you want to attend yet? has thousands of articles about every imaginable degree, area of study and career path that can help you find the school that's right for you.

Create an account to start this course today
Try it risk-free for 30 days!
Create an account