 When representing the electrical circuit parameters as vectors in a complex plane, known as phasors, a capacitor's loss tangent is equal to the tangent of the angle between the capacitor's impedance vector and the negative reactive axis, as shown in the adjacent diagram.The loss tangent is then

Since the same AC current flows through both "ESR" and "Xc", the loss tangent is also the ratio of the resistive power loss in the ESR to the reactive power oscillating in the capacitor.For this reason, a capacitor's loss tangent is sometimes stated as its "dissipation factor", or the reciprocal of its "quality factor Q", as follows