Question

In case of a transistor, the central portion has to be :

Answer 1

Transistor:

1. The transistor is an extension of the junction diode and consists of a single crystal of semiconductor with two p-n junctions.
2. Junction transistors can be of two types p-n-p type and n-p-n type.
3. If a layer of n-type material is sandwiched between two p-type layers, the transistor is referred to as p-n-p type.
4. On the other hand, if a layer of p-type material is sandwiched between two n-type layers, the transistor is called n-p-n type.
5. The central layer is made very thin and lightly doped as compared with the two outer layers and is called the base.
6. The outer sections are called emitter and collector.
7. The emitter layer is heavily doped and the collector layer is lightly doped.
8. For normal operation, emitter-base junction is forward biased and the collector-base junction is reverse biased.
9. Say for an p-n-p transistor, the emitter injects holes into the base and these holes are finally collected by the collector.
10. Hence, the central portion can be p-type or n-type depending on the type of transistor that is being used.