If capacitors and inductors are connected in series with a generator, series resonance will occur as long as the reactance is equal. In this case, the active part Z should be as small as possible.

It should be noted that in ideal examples, inductors and capacitors only have reactive quality. In practical circuits and components, the active resistance of conductors always exists, even though it is small.

During resonance, energy is exchanged between the inductor and the capacitor. In an ideal example, when initially connected to an energy source (generator), energy accumulates in capacitors (or chokes), and after shutdown, continuous oscillations occur due to this exchange.

According to Ohm's Law, the voltage across an inductor and a capacitor is roughly the same:

U = I / X

Among them, X represents Xc capacitor or XL reactance respectively.

A circuit composed of inductors and capacitors is called a series resonant (or variable frequency resonant) circuit.

Due to the fact that reactance depends on frequency, inductance and resistance increase with increasing frequency, while capacitance decreases. When the resistance is equal, the total resistance will significantly decrease.

The main characteristics of a circuit are quality factor (Q) and frequency. If we consider the circuit as a four port network, after simple calculations, its transmission coefficient will decrease to the quality factor: K=Q, and the voltage at the circuit terminals will increase proportionally to the transmission coefficient (quality factor) of the circuit.