Basic Qualification · B-005 Basic electronics and theory · B-005-012-010
Resonance is the condition that exists when:
- A inductive reactance and capacitive reactance are equal and opposite in sign
- B inductive reactance is the only opposition in the circuit
- C the circuit contains no resistance
- D resistance is equal to the reactance
Correct answer: A — inductive reactance and capacitive reactance are equal and opposite in sign. From the official ISED question bank, verified word for word.
Why
Resonance happens when the opposition to current from an inductor (inductive reactance) exactly matches the opposition from a capacitor (capacitive reactance), but they push in opposite directions, effectively cancelling each other out. 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.