Question

What is the active region of the transistor?
A. Active region is that region in which emitter base junction is forward bias while collector base junction is also forward bias
B. Active region is that region in which emitter base junction is forward bias while collector base junction is reverse bias.
C. Active region is that region in which emitter base junction is reverse bias while collector base junction is reverse bias
D. Active region is that region in which emitter base junction is reverse bias while collector base junction is forward bias,

Answer 1

Hint: To solve the question, we must know that Active region of the transistor is the region in which the transistor behaves normally. A transistor in an active region behaves like an amplifier. To achieve amplifying action of the transistor its input and output junctions must be biased accordingly.

Complete answer:
A transistor is a three terminal device that has an emitter, base, and a collector. For a common base configuration, the input terminal is the emitter-base terminal and output terminal is the base-collector terminal. In the active region the emitter base (input region) junction is forward bias, and the base collector (output) junction is reverse bias.

Now, we will look at the circuit in which a transistor is connected in common base configuration.

Then, the graph showing its active and saturation region will be,

Active region is that region in which the emitter base junction is forward biased while the collector base junction is reverse biased.

So, the correct answer is “Option B”.

Additional Information:
The transistor is in the cut off region when both E-B and B-C junctions are reverse biased and in the saturation region when both E-B and B-C junctions are reverse biased.

Note:
Students must remember that the active region of the transistor is the linear region between the cut off and saturation region in which amplifying action of the transistor is seen. In the cut off region the transistor acts as an off switch and in saturation region it behaves like an on switch.