Page 971 - Basic Electrical Engineering

Figure 14.14 (a) Block representation, two-diode transistor analogy, and symbol of a n–p–n
transistor; (b) block representation, two-diode transistor analogy, and symbol of a p–n–p transistor

The symbolic representation of a transistor has also been shown. The

symbol for an n–p–n or a p–n–p transistor is the same except for the direction
of the arrow head. The arrow head has to be shown from p terminal to n
terminal between the emitter and the base. The emitter of a transistor is

heavily doped. The base is lightly doped while the collector is less heavily
doped than the emitter.

14.7.1 Working of a n–p–n Transistor

For a transistor to work, it has to be biased by applying external voltage
supply with proper polarity. For operation in the active region, a transistor’s