Question

What is a transistor? Distinguish between NPN transistor and PNP transistor?

Answer 1

Hint: Firstly, we will learn about transistors and the concept behind them. We will also understand the role of transistor and study its types (PNP(p-n-p) and NPN(n-p-n) transistor). Then we will learn about the features that distinguish between them and types of blocks that they are containing and its features. This information will lead us in approaching our answer.

A transistor is a semiconductor device used to switch electronic signals or amplify signals and electric power. It's composed of semiconductor material usually with three terminals (for connection to an external circuit).

Complete step by step answer:

Basis for comparison	NPN Transistor	PNP Transistor
Definition	Negative positive and negative Transistor in which two n- type layer are separated by one P-type layer	Positive negative and positive Transistor in which two blocks of P- types semiconductors are split by one thin block of n-type semiconductor .
Direction of current	Flows from collector to Emitter	Flows from emitter to collector
Turn- on	When an electron enters into the base.	When holes enter into the base.
Inside current	Inside it develops because of the varying position of electrons.	Develop because of the varying position of holes.
Outside current	Outside the current develop due to flow of holes	The current develops due to flow of electrons.
Positive Voltage	Collector Terminal	Emitter Terminal
Small Current	It flows from emitter- to-base	It flows from base to emitter

The transistor in which one p-type material is placed between two n-type materials is known as NPN transistor NPN transistors has electrons as a majority charge carrier whereas PNP transistor has a hole as majority charge carrier. If we talk about its mobility then mobility of electrons is better than holes. Also, NPN transistors amplifies the signal which is weak enter into a base and produces strong amplify signals to the end name as a collector that's we say that the NPN transistor the current flow between collector to emitter whereas in PNP transistor the charge carrier flows from emitter to collector as the negative supply is given to base. These both transistors are the bipolar junction transistor. The electrons are more mobile, the NPN has high conduction so this is the reason why we mostly use NPN transistors in the circuit as in NPN transistors the conduction current mainly by electrons while in PNP transistors the hole is the reason for conduction current. The Switching time is faster in NPN transistor and slower in PNP transistor. The positive voltage is collector terminal in NPN transistor and emitter terminal in PNP transistor.
Most of the time it is seen as a PNP transistor that can replace NPN transistors in most electronic devices, the only difference here in polarity voltages, and the direction of its current flow.

Note:
If we want a good NPN transistor, you should see "OL"(Over Limit). If you want to test PNP transistor, the meter should show a low voltage drop between 0.45V and 0.9V. Then hook the positive lead from the multimeter to the Collector(C) of the transistor with us and if u hook the negative meter lead to Base(B) of the transistor.
Generally, it is seen that NPN is more popular in the US and PNP is more widely used in Europe.