Power Factor
The cosine of angle between voltage and current in an a.c. circuit is known as power factor. In an a.c. circuit, there is generally a phase difference φ between voltage and current. The term cos φ is called the power factor of the circuit. If the circuit is inductive, the current lags behind the voltage and the
power factor is referred to as lagging. However, in a capacitive circuit, current leads the voltage and power factor is said to be leading.