Topic 23. Transistor Action
Electronic components are of two kinds — passive and active. Passive devices are not able to generate an increase of power. Examples include resistors, capacitors and inductors. Resistors are able to convert electrical power to heat. Inductors are able to convert electrical energy into magnetic force. But neither of these devices is able to increase the power in the circuit. They are passive. In contrast, a transistor has a low-power input (small current) and converts this to a high-power output (large current). It is an active component. The energy for this activity comes from the electrical supply to the circuit.