The average ac power is found by multiplying the rms values of current and voltage.  Ohm’s law for the rms ac is found by dividing the rms voltage by the impedance. In an ac circuit, there is a phase angle between the source voltage and the current, which can be found by dividing the resistance by the impedance. The average power delivered to an RLC circuit is affected by the phase angle. The power factor ranges from –1 to 1

At the resonant frequency, inductive reactance equals capacitive reactance. The average power versus angular frequency plot for an RLC circuit has a peak located at the resonant frequency; the sharpness or width of the peak is known as the bandwidth. The bandwidth is related to a dimensionless quantity called the quality factor. A high-quality factor value is a sharp or narrow peak.