EASA Module 3 · Resonant Circuits

Series LC Resonance

At the resonant frequency, X_L and X_C cancel, impedance is at a minimum and current peaks. Change L, C and the damping R and watch the resonance curve shift and sharpen.

Inductance L 10 mH

Capacitance C 1.0 µF

Resistance R (damping) 20 Ω

Resonant f₀

—

Peak current

—

Q factor

—

Bandwidth

—

f₀ = 1 ÷ (2π√(LC)). A lower R gives a taller, sharper peak — a higher quality factor Q = (1/R)√(L/C) — and a narrower bandwidth. This selectivity is how radios tune to one station.