Basic Qualification · B-004 Circuit components · B-004-005-008
What is inside the envelope of a triode tube?
- A Neon
- B A vacuum
- C Argon
- D Air
Correct answer: B — A vacuum. From the official ISED question bank, verified word for word.
Why
A triode tube works by letting electrons flow freely from a heated filament to a plate, which requires an empty space inside the glass envelope so nothing blocks their path. 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.