In a series LC circuit, when the capacitive reactance equals the inductive reactance, what happens to the total impedance?

In a series LC circuit, when the capacitive reactance equals the inductive reactance, this condition is referred to as resonance. At this point, the inductive reactance (XL) and capacitive reactance (XC) effectively cancel each other out.

The total impedance of the circuit is determined by the vector sum of the resistive and reactive components. When XL equals XC, the reactive component becomes zero, meaning that what remains is only the resistive component of the circuit. Consequently, the total impedance approaches its minimum value, which is purely resistive. This is important in the context of resonance because at this minimum impedance, the circuit can draw the maximum current for a given voltage, maximizing the power transfer in the circuit.

This low impedance state is highly significant when designing circuits that need optimal signal transfer, such as in radio frequency applications or resonance-based filters.