What is the effect of frequency on the impedance of a resonant circuit?

The impedance of a resonant circuit is lowest at its resonant frequency.

When an AC voltage is applied to a resonant circuit, the circuit's impedance varies with frequency. At the resonant frequency, the circuit's impedance is at its minimum value, which is equal to the resistance of the circuit. This is because at resonance, the reactive components of the circuit (inductance and capacitance) cancel each other out, leaving only the resistive component.

At frequencies above or below resonance, the circuit's impedance increases due to the reactive components. At frequencies below resonance, the inductive reactance dominates and the impedance increases with decreasing frequency. At frequencies above resonance, the capacitive reactance dominates and the impedance increases with increasing frequency.

The frequency response of a resonant circuit can be graphed using a resonance curve, which shows the variation of impedance with frequency. The resonance curve has a sharp peak at the resonant frequency, indicating the low impedance at resonance. The width of the peak, known as the bandwidth, depends on the quality factor (Q) of the circuit. A higher Q value results in a narrower bandwidth and a sharper resonance peak.

In summary, the impedance of a resonant circuit is lowest at its resonant frequency, where the reactive components cancel each other out and only the resistive component remains. The frequency response of a resonant circuit can be graphed using a resonance curve, which shows the variation of impedance with frequency.