What is transistor explain with working and constructional diagram?

  INTRODUCTION:-

The transistor is basicially amplifying action is produced by transferring a current from a low resistance to high resistance circuit.

Full detail in short term:-

• It is a current current controlling device.
• Trans means transfer of current and istor means register:- low resistance to high resistance.
• Transistor is basically used for amplifying.
• It has three terminal.
• Emitter, Base and collector.
• All terminal is taken from each three type of layer which is made up of semiconductor.
• Transistor is made up of semiconductor material.
• It is a current controlling device.
• There are two types of BJT transistor:- NPN & PNP transistor.
• These are made up of two diodes connected back to back.

When 3rd doped element is added to a crystal diode in such a way that two PN junction are formed the resulting device is known as transistor.
Transistor consists of two PN junction formed by sandwitching, either P type or n type semiconductor between a pair of opposite types of material.
The middle section in a very thin layer this is the most important factor in the function of transistor.

Explanation of all three terminal:-

Constructional block diagram of two transistor 

1. Emitter:- The section on one side that supply charge Carriers is called the emitter. The emitter is always forward biased with respect to base so that it can supply a large number of of majority carriers.

2. Collector:- The section on the other side that collect that charge is called collector. The collector is always reverse biased. It functions is to remove charge from its junction with the base .

3. Base:- The middle section which forms two PN junction between the emitter and collector is called the base. The the base emitter junction is forward biased, allowing low resistance for the emitter circuit. The base collector junction is Reverse bias and provide high resistance in the collector circuit.

Applications:-

 amplifiers apparatus.
 As amplifiers, they are being also used in various oscillators, modulators, detectors.
As switch in switching apparatus.