DESCRIPTION OF PARTS

The telephone consists of the following parts:-

1. ELECTRICAL COMPONENTS

(a) Transmitter

(b) Receiver

(d) Amplifier

2. MECHANICAL COMPONENTS

(a)Dialler

(b)Cradle

The mechanical components have been separayely dealt with in the explanation of theMechanical System

TRANSMITTER:-

The transmitter is the device that converts the sound signal (voice) into a corresponding electrical signal.It comprises of graphite granueles enclosed between two metallic plates ,one of which remains stationary. The other plate, the diaphragm, is very thin, & vibrates with the sound wave. A voltage is applied across the plates. Thus , as the diaphragm vibrates with the sound waves, the graphite granules either get packed more tightly or less tightly , changing the resistance of the arrangement , thereby altering the current.Thus the sound signal gets electrically stored. This is then sent across the telephone wires.

RECEIVER:-

The receiver is the device that takes as input the electrical signal (produced by the transmitter at the speaker's end) and converts it into sound. The receiver basically consists of a diaphragm, which is a thin disc of a ferrous material, which when vibrated produces sound ; and a coil , which acts as an electromagnet when current is passed through it. The diaphragm is supported along its periphery so that it is free to vibrate, while the coil is placed below it , such that when it gets magnetised , it pulls the diaphragm downwards (towards itself), & when demagnetised , lets the diaphragm move back on its own.Thus when the varying current from th espeakers transmitter is fed into the coil of the receiver , it gets magnetised, and the strength of the magnet varies in accordance with the variation in the current. This makes the diaphragm vibrate , therby producing sound & hence fulfilling its purpose.

RINGER:-

The ringer is a device which alerts the receiver of an incoming call. It basically functions as an electric bell.The basic principle is as follows:-

The sound is produced by the striker striking the gongs repeatedly.The striker forms part of the electrical circuit,which when allowing current to pass through activates a coil, making it act like a magnet, which thus pulls the striker towards it, making the striker strike the gong.No sooner does the striker move, than the circuit is broken.As the striker strikes the gong , it also completes the circuit for a second coil which pulls it back , thus making the striker strike the second gong and complete the original circuit.And thus thye process continues , and the ringer rings continuously.

AMPLIFIER:-

The amplifier is a device which amplifies the input electrical signal.It converts the weak input signal into a much stronger output signal.

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