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This helps a lot while solving numerical problems. One thing to note here is the current direction in both NPN and PNP transistors. The symbol of the PNP transistor is the same as fig. The meeting point of the two diodes (cathode) becomes the base terminal and the two anodes at the extremes become the emitter and collector of the NPN transistor. The construction can be understood by visualizing two diodes connected one after the other (see the above figure).

Therefore, in the case of PNP, the emitter and collector region connects to the P-type semiconductor and base to that with N-type. Emitter and collector are always on the two extremes. In PNP the two P-type regions are there on the extreme and an N-type region is in between the two. The only difference in the symbols of the two transistors is that in NPN, the current direction is from base to emitter and in PNP it’s opposite, i.e., from emitter to base. In NPN, the P-type semiconductor is sandwiched between the two N-type semiconductors.

Bipolar junction Transistor is of two types, namely, NPN and PNP. Hence, the name current controlled device. Therefore, it’s like we can control the transistor action by differing the amount of applied current at the base terminal. It has three terminals in which the current applied to the base region controls the current flow in the emitter and collector. It is useful in switching circuits electronically. Popularly known as BJT, is a solid-state current controlled device. Thus, let us learn more about all this in the upcoming sections. To understand these carriers, terminals, and many more we need to go through the basics of transistors. In PNP transistors, the majority charge (current) carriers are holes and the electrons are the minority charge carriers. These diodes make junctions as are connected one after another and are called collector-base and base-emitter junction. The PNP transistor acts as two PN junction diodes connected one after another. The terminals are namely, emitter (E), base (B), and collector (C). This transistor is a three-terminal device.

It is made by sandwiching an n-type semiconductor between the two p-type semiconductors. A PNP transistor is nothing but a bipolar junction transistor (BJT).