Basic Qualification · B-005 Basic electronics and theory · B-005-012-009
Resonant circuits in a receiver are used to:
- A select the desired signal frequencies
- B filter direct current
- C amplify audio signals
- D adjust voltage levels
Correct answer: A — select the desired signal frequencies. From the official ISED question bank, verified word for word.
Why
Resonant circuits act like a tuning fork for radio waves, vibrating strongly only at one specific frequency while ignoring others, which allows the receiver to pick out your desired station from the airwaves. The full explanation — and one for every question — is in Pro.
Practise this section
The theory: Ohm's law, power, series and parallel circuits, AC and DC, frequency and wavelength, decibels, and the metric prefixes the exam leans on.