MP Board · Class 12 · Physics · Alternating CurrentDefine Power Factor of an AC circuit. What are its maximum and minimum values?

The power factor of an alternating current circuit is defined as the cosine of the phase angle ($\phi$) between the voltage and the current in that circuit. Mathematically, Power Factor = $\cos \phi = \frac{R}{Z}$, where $R$ is resistance and $Z$ is impedance. The value of the power factor lies strictly between 0 and 1. The maximum value of power factor is 1, occurring in a purely resistive circuit where $\phi = 0^\circ$. The minimum value is 0, occurring in purely inductive or purely capacitive circuits where $\phi = 90^\circ$.