UPSC CDS Science Physics Questions Part 1

In a bipolar junction transistor, the base has the least concentration of impurity. A transistor is basically a Si on Ge crystal containing three separate regions. It can be either NPN or PNP type. The middle region is called the base and the outer two regions are called the emitter and the collector. Emitter has the highest and base has the least concentration of impurity. Collector has the moderate concentration of impurity.