Bipolar Junction Transistor (N-P-N And P-N-P Transistor) - Practice Questions & MCQ

Bipolar Junction Transistor (BJT)-

it is a three-terminal electronic device that amplifies the flow of current. It has three doped regions ( emitter, base, and collector) forming two p-n junctions between them. 

Based on their construction, Bipolar junction transistors are classified into two types as 

1) n-p-n transistor

  2)  p-n-p transistor-

All three segments (emitter, base, and collector) of a transistor have different thickness and their doping levels are also different.

The schematic symbols of both these transistors are given in the below figure.

In the schematic symbols, as shown in the above figure, the arrowhead shows the direction of conventional current in the transistor.

The three segments of a transistor-

• Emitter- This segment is on one side of the transistor. It is of moderate size and heavily doped causing it to supply a large number of carriers for the flow of current.
• Base: This is the central segment. It is very thin and lightly doped.
• Collector: This segment collects a major portion of the majority carriers supplied by the emitter. The collector side is moderately doped and larger in size as compared to the emitter.