What is a telephone?
A telephone is a device used for communication over long distance. It converts sound, especially the human voice, into electronic signal that are transmitted over lon distances via cables or other transmission media. Since its invention, the telephone has been greatly improved an many variants of the original prototype have been developed to serve the various need of people. Today, telephone are indispensable to businesses, government, offices and households.
When was the telephone invented and by whom?
The telephone was first patented in 1876 by Alexander Graham Bell, though its invention was the culmination of work done by many individuals, simultaneously. Bell wanted to improve the telegraph, a wire based electrical system that had been an established means of communication. The telegraph was basically limited to receiving and sending one message at a time. Bell designed a 'harmonic telegraph', which was based on the principal that several notes could be sent simultaneously along the same wire, if the notes or signal differed in pitch.
What are the part of a telephone?
How does a telephone work?
A telephone's mouthpiece that contain a transmitter has a thin, round metal disk called a diaphragm. When a person talks into the telephone, the sound wave strike the diaphragm and make it vibrate. The diaphragm vibrates at various speeds,depending on the variations in air pressure caused by the varying tones of the speaker's voice. Behind the diaphragm lies a small cup filled with tiny grains of carbon which, which contain a low voltage electric current. Louder sound create stronger vibrations that squeeze the carbon grains more loosely. As the vibrating diaphragm presses against these carbon grains, the current copies the pattern of the sound waves and travels over a telephones wire to the receiver of another telephone. The receiver also a diaphragm with two magnets - a permanent magnet that constantly holds the diaphragm close to it stronger or weaker according to the loud or soft sounds. This action causes the diaphragm to vibrate according to the speaker's speech pattern. As the diaphragm moves in and out, it the same as the ones sent into the transmitter. The sound wave strike the ear of the listener and he hears the words of the speaker.
How many types of telephones are there?
Telephone are made in variety of form. A landline telephone is connected by a pair of wires to the telephone network, while a mobile phone communicates through radio transmission. A cordless telephone has a portable handset base station which is connected by a wire to the telephone network.
what is the structure of a telephone network ?
The telephone network consists of a worldwide net of telephone line, fibre optic cable, microwave transmission, cellular network, communications satellites, and undersea telephones cable connected by switching centers.