Basic Qualification · B-004 Circuit components · B-004-003-010
When a bipolar transistor is used as a switch, which electrode controls its state?
- A Base
- B Emitter
- C Collector
- D Gate
Correct answer: A — Base. From the official ISED question bank, verified word for word.
Why
In a bipolar transistor, the Base acts as the control valve; a small current entering this terminal allows a much larger current to flow between the other two terminals, effectively turning the device on or off like a switch. The full explanation — and one for every question — is in Pro.
Practise this section
The parts inside the box: resistors, capacitors, inductors, diodes, transistors, tubes and what each does in a circuit.