Magnetism And Electromagnetism - Telephone Receiver

Points : Telephone Receiver, Working Definition The ear pieces of a telephone receiver, receives sound waves converted into electric signal and converts the electric signal as into sound waves of the same frequency as the sound frequency of the speaker on the other side.
• The car pieces consist of a permanent magnet in contact with two soft iron cores. The respective coils of the insulated wire of the cores are wound in opposite directions.
• A diaphragm made of magnetic alloy is positioned in front of the iron core.
Working: When a messages is received.
• The sound energy’ transformed in electric current is received by the ear pieces.
• The electric current received varies in magnitude depending upon the frequency of the sound waves.
• At the receiver the current passes through the electromagnet coil and energies the magnet.
• Thus the magnetic held effect varies the current. Due to this the magnetic diaphragm pulling force also varies.
• The diaphragm vibrates and gives rise to sound of the same frequency as that spoken at the other hand.