RLC Resonance Analyser

Q is a general measure of stored energy divided by energy lost per cycle. In a series RLC circuit, low resistance lets energy shuttle many times between the inductor magnetic field and capacitor electric field before it becomes heat. The same idea appears in atomic clocks: a narrow spectral linewidth means an enormous Q, so the oscillator can distinguish extremely small frequency errors.

Every inductor–capacitor pair has a natural frequency, f₀ = 1/(2π√(LC)), where energy sloshes back and forth like a child pumping a swing. Drive the circuit at f₀ and the reactances of L and C cancel, leaving only the resistance — so the current peaks sharply. Notice that f₀ depends only on L and C: turning the resistance knob sharpens or broadens the peak, but never shifts it.

At resonance the source only "sees" the resistance, yet the voltage across the inductor and the capacitor each swell to Q times the input — and, being 180° out of phase, they cancel exactly. Drive a Q = 50 circuit with 10 V and the capacitor sees 500 V. This voltage magnification is how spark-gap transmitters and Tesla coils reach huge voltages, and it can quietly destroy a capacitor rated only for the input.