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Explain the applications of junction diodes

Explain the applications of junction diodes.

Answers

They are mainly used for rectification of a.c. current for use by many electrical appliances. Rectification is the conversion of sinusoidal waveform into unidirectional (non-zero) waveform.

1. Half wave rectification
In this case the first half cycle of a sinusoidal waveform is positive and the inclusion of a reverse biased diode makes the current not to flow to the negative side of the wave. The current therefore conducts on every half cycle hence a half wave rectification is achieved.
The voltage is d.c. and always positive in value though it is not steady and needs to be smoothed by placing a large capacitor in parallel to the load as shown.


2. Centre-tap full wave rectification
This is achieved by using a transformer whose output has a centre tap that is taken at two points where one is half the other as shown.


3. Bridge full wave rectification In this case a bridge rectifier is used to achieve a full wave rectification. The current flows in the same direction in both half cycles.


4. Radio transmitter and receiver
Radio waves are produced by circuits that make electrons vibrate and they are known as oscillators which produce varied frequencies. Since radio waves have greater range in air than sound or even light waves they are used as carriers of audio (sound) and visual information (TV) waves.
The sound is first changed into electrical vibrations by use of a microphone or other device then added to the radio carrier wave and this changes the amplitude of the carrier and is called amplitude modulation. The modulated wave is given out by the transmitting aerial and received by another aerial in a radio or TV when they cause vibrations between the earth and the aerial. They are then demodulated by a diode and hence heard as a sound or image.

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Mutiso answered the question on October 18, 2018 at 18:29

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