Basic Qualification · B-008 Interference and suppression · B-008-002-008
What device can be used to minimize the effect of RF pickup by audio wires connected to stereo speakers, intercom amplifiers, telephones, etc.?
- A Coil on ferrite core
- B High-pass filter
- C Attenuator
- D Surge suppressor
Correct answer: A — Coil on ferrite core. From the official ISED question bank, verified word for word.
Why
A coil on ferrite core works by wrapping the audio wire around a special iron-like bead that acts as a trap for unwanted radio frequency energy, stopping it from turning into noise in your speakers or phones. The full explanation — and one for every question — is in Pro.
Practise this section
When things interfere: harmonics, overload, RFI to and from your station, filters, ferrites and how to fix the neighbour's TV.