The Telephone System

Essay by Anonymous UserHigh School, 12th grade February 1996

download word file, 4 pages 4.8

The telephone is one of the most creative and prized inventions in the world. It has advanced from its humble beginnings to its wireless communication technology today and for the future. The inhabitants of the earth have long communicated over a distance, which has been done by shouting from one hilltop or tower to another. The word 'telephone' originated from a combination of two Greek words: 'tele', meaning far off, and 'phone', meaning voice or sound, and became the known term for 'far- speaking.'

A basic telephone usually contains a transmitter, that transfers the caller's voice, and a receiver, that amplifies sound from an incoming call. In the transmitter there are two common kinds of transmitters: the carbon transmitter, and the electret transmitter. The carbon transmitter uses carbon granules between metal plates called, electrodes, with one consisting of a thin diaphragm that moves by pressure from sound waves and transmits them to the carbon granules.

These electrodes conduct electricity flowing through the carbon. The sound waves hit the diaphragm causing the electrical resistance of the carbon to vary. The electret transmitter is composed of a thin disk of metal-coated plastic held above a thicker, hollow metal disk. This plastic disk is electrically charged, and creates an electric field. The sound waves from the caller's voice cause the plastic disk to vibrate, changing the distance between the disks, thus changing the intensity of


the electric field. These variations are translated into an electric current which travels across the telephone lines. The receiver of a telephone is composed of a flat ring of magnetic material. Underneath this magnetic ring is a coil of wire where the electric current flows. Here, the current and magnetic field from the magnet cause a diaphragm between the two to vibrate, and replicate the sounds that...