Explain the operating principle of PNP transistor.

Explain the operating principle of PNP transistor. 
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Answer :

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The circuit connection of PNP transistor with supply voltages is as shown above. The emitter-base junction is connected as forward bias. Due to this the emitter pushes the holes from the P type emitter region across the emitter-base junction into the base region. These holes constitute the emitter current IE. When these holes move into the N-type semiconductor material or base, they combined with the electrons. The base of the transistor is thin and very lightly doped. Hence only a few holes combined with the electrons and the remaining are moved towards the wide and medium doped P type collector region. This is the base current IB. The collector base region is connected in reverse bias. The holes which collect around the depletion region when coming under the impact of negative polarity collected or attracted by the collector. This develops the collector current IC. This is how a PNP transistor operates. 

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