How much power is dissipated in an RLC circuit? First, remember that no energy is lost in inductors (these store energy in the magnetic field) or capacitors (these store energy in the electric field). Only resistors dissipate energy, and the resistance is the cos(f) component of Z, so:

The average power dissipated in an AC circuit is:

P = V_rmsI_rms cos(f)

cos(f) is known as the power factor for the series RLC circuit.