The difference between npn and pnp junctions.

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NPN and PNP junctions are types of bipolar junction transistors with different arrangements of layers and doping.

NPN transistor has a layer of p-type semiconductor sandwiched between two layers of n-type semiconductor, while PNP transistor has a layer of n-type semiconductor between two layers of p-type semiconductor.
In NPN transistor, majority charge carriers are electrons, while in PNP transistor, majority charge carriers are holes.
NPN transistors are more commonly used in digital and analog circuits compared to PNP transistors.
Examples of NPN transistors include 2N2222, BC547, while examples of PNP transistors include 2N3906, BC557.

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