ELECTRONIC COMPONENTS

Transistors.
They are made from semiconductor materials and have three electrodes called the base, the collector and the emitter.
There are two types of transistor: NPN and PNP.

-When no electrons are flowing through the base, then no electrons can pass from the collector to the emitter. The transistor is in cut off.

- When many electrons are flowing through the base, the route between the collector and the emitter will be completely open. The transistor is in saturation.

- When the flow of electrons through the base is between the cut off and saturation levels, it will be proportional to the flow of electrons between the collector and the emitter. The transistor is in the active region.