73) For useful amplifying action, which of the following features should a transistor have?

The emitter should be heavily doped, the collector less heavily doped and the base lightly doped

The area of the base-collector junction must be larger than that of the emitter base junction

All these features

The thickness of the base layer should be very small

Answer is:

All these features

Explanation:

The transistor have all the given features in option

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74) In P-N- P transistor operating as an amplifier with common emitter configurations a change in base current from 100 mA to 200 mA produces a change in collector current from 10 mA to 18 mA. The current gain of transistor is

12.5*10^-3

25*10^-3

Answer is:

80

Explanation:

ALPHA (?):?It is a large signal current gain in common base configuration. It is the ratio of collector current (output current) to the emitter current (input current).It is a current gain in CB amplifier and it indicates that the amount of emitter current reaching to collector. Its value is unity ideally and practically less than unity. Beta (?): It is a current gain factor in the common emitter configuration. It is the ration of collector current (output current) to base current (output current).