Electronics - Telephone

Telephone Points : Telephone, Construction, Carbon Microphone, Magnetic Earphone, Dial, Bell, Working Definition It is an electronic device, which is used, for conversation over long distances. Construction: Telephone consists of following parts,
• A Carbon microphone
• Magnetic earphone
• Dial
• A bell of alarm
Carbon Microphone: The carbon microphone has a thin metal plate called a diaphragm suspended in front of packing of carbon granules. Magnetic Earphone: Magnetic earphone has a thin steel plate suspended in front of an electromagnet. In telephone net work two wires are used. Dial: It is used for dialing a number. When a number is dialed pulses are generated which contain the information of dialed number. Bell: Ringing of the bell or alarm indicates the arrival of a call from a certain number. Working: When someone speak in front of a microphone, compression and rarefaction of sound cause the diaphragm to vibrate. These vibrations increase or decrease the pressure on the carbon granules very rapidly. Since granules are part of the circuit, the current fluctuates in harmony with the sound waves. On the other side sound waves are converted into electrical fluctuations by the microphone at one end and the electrical fluctuations are converted into sound waves by the earphone.