The correct answer is: A. Proper forward bias.
A transistor is a semiconductor device used to amplify and switch electronic signals and electrical power. It is composed of semiconductor material with at least three terminals for connection to an external circuit. A voltage or current applied to one pair of the transistor’s terminals changes the current through another pair of terminals. Because the controlled (output) power can be higher than the controlling (input) power, a transistor can amplify a signal. Today, some transistors are packaged individually, but many more are found embedded in integrated circuits.
A transistor can be thought of as two semiconductor diodes connected back to back with a thin layer of semiconductor material between them. The two diodes are called the emitter and collector, and the thin layer is called the base. When a small voltage is applied to the base-emitter junction, it creates a large current flow between the emitter and collector. This current flow can be used to control a much larger current flow in an external circuit.
The proper forward bias of a transistor is achieved by applying a positive voltage to the base-emitter junction and a negative voltage to the collector-emitter junction. This causes a current to flow through the base-emitter junction, which in turn causes a much larger current to flow through the collector-emitter junction.
The other options are incorrect because:
- Option B: The collector should have proper forward bias, not reverse bias.
- Option C: The size of the collector does not affect its operation.
- Option D: None of the above is correct.