Where is the PNP transistor used?

Hint: The transistor is basically a 'semiconductor device' which can move a poor signal from the circuit which has a lower resistance to another circuit of higher resistance. PNP transistor belongs to the category of ‘Bipolar Junction Transistor’. Note that ‘PNP’ is the abbreviation of ‘Positive Negative Positive Transistor’.

Complete answer:
A transistor is a device of semiconductor that is used in signal amplification and also for circuit switching. In general, a transistor is composed of three terminals for connecting to other circuit elements: base (B), emitter (E), and collector (C). A few other transistors have a fourth terminal, which is the substrate (S).

PNP or Positive negative positive transistor is a part of BJT or Bipolar Junction transistor.PNP transistors are made up of two semiconductor elements of the p-type, which are separated by a thin stage of semiconductor of n-type. In PNP transistors, holes are indeed the majority charge carriers, so naturally electrons will act as the minority charge carriers.

Electric current flows from the 'Emitter to Collector' in a PNP transistor.Note that the gate controller unit for increased supply of electricity is termed as the ‘base’. Then increased electrical supply will be the ‘collector’, and the ‘emitter’, its outlet.

PNP transistors have a broad range of purposes (uses), some of which are mentioned below:
-There are some robotic applications that are able to utilize PNP transistors.
-For making 'switches' that perform on/off functionalities within a circuit, PNP transistors may be utilized.
-Darlington pair circuits as well employ PNP transistors.
-Amplification circuits (signal magnitude increasers) also make use of PNP transistors.
-PNP transistors at times may be used to monitor the movement of current in high-power applications.

Note: The functionalities of PNP and NPN transistors are completely contradictory. As current is applied towards the base junction of the transistor, NPN (Negative positive negative transistor), it allows more power to pass through it, which is why NPN transistors are said to be great for amplifiers. PNP, on the other hand, does the contrary: it turns off when current is applied.