A
both collector and emitter are positive with respect to the base
B
collector is positive and emitter is negative with respect to the base
C
collector is positive and emitter is at same potential as the base
D
both collector and emitter are negative with respect to the base
The answer is B.
Solution
A transistor conducts (in the active region) when the emitter-base junction is forward biased and the base-collector junction is reverse biased. In an n-p-n transistor, the emitter is n-type and the base is p-type. Forward bias of the emitter-base junction means the base (p) is positive with respect to the emitter (n), i.e. the emitter is negative with respect to the base. Reverse bias of the base-collector junction means the collector (n) is positive with respect to the base (p). So the n-p-n transistor conducts when the collector is positive and the emitter is negative with respect to the base.
ConceptActive region biasing of npn transistor
Semiconductor Electronics: Materials, Devices and Simple Circuits in past papers
106 questions from this chapter have appeared across 24 exam years.
