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Q)

Which of the following are incorrect statements about a transistor?

(1) The emitter is always forward biased with respect to the base

(2) The base is always heavily doped to inject a large number of charge carriers or electrons

(3) The transistor has 2 pn junctions, i.e, its like 2 diodes

(4) The resistance of the emitter is very large as compared to the collector

(1): TRUE: The emitter is always forward biased with respect to the base $\rightarrow$ The section on one side that supplies charge carriers (electrons or holes) is called the emitter. The emitter is always forward biased w.r.t. base so that it can supply a large number of *majority carriers.
(2):FALSE: The base is always heavily doped to inject a large number of charge carriers or electrons $\rightarrow$ The base is lightly doped and very thin ; it passes most of the emitter injected charge carriers to the collector, the emitter is always heavily doped.
(3): TRUE: The transistor has 2 pn junctions, i.e, its like 2 diodes $\rightarrow$ The junction between emitter and base may be called emitter-base diode or simply the emitter diode. The junction between the base and collector may be called collector-base diode or simply collector diode.
(4) FALSE: The resistance of the emitter is very large as compared to the collector $\rightarrow$ The resistance of emitter diode (forward biased) is very small as compared to collector diode (reverse biased). Therefore, forward bias applied to the emitter diode is generally very small whereas reverse bias on the collector diode is much higher.