Реферат: The Telephone System Essay Research Paper The

The Telephone System Essay, Research Paper

The Telephone System

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 are

transformed into electricity.

The telephone is also composed of an alerter and a dial. The alerter,

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