General exam question G5A01
Subelement G5, ELECTRICAL PRINCIPLES· Group G5A
What happens when inductive and capacitive reactance are equal in a series LC circuit?
- A.Resonance causes impedance to be very high
- B.Impedance is equal to the geometric mean of the inductance and capacitance
- C.Resonance causes impedance to be very low (correct answer)
- D.Impedance is equal to the arithmetic mean of the inductance and capacitance
WhyWhen inductive and capacitive reactance are equal in a series LC circuit, resonance causes impedance to be very low. At resonance in a series LC circuit, inductive and capacitive reactance are equal and opposite, so they cancel each other out completely, leaving only whatever pure resistance is present in the circuit, which drives impedance down to a very low value, answer C. Impedance falls rather than rises at series resonance, ruling out A, and impedance isn't computed as a geometric or arithmetic mean of the component values, so B and D describe the wrong relationship entirely.
Published 2026-08-28 · Last updated 2026-08-28 · Question text is verbatim from the 2023-2027 NCVEC Element 3 pool (public domain); the explanation above is original writing, see our methodology.