When is a circuit's power factor equal to 1?

A circuit's power factor is a measure of how effectively the circuit converts electric power into useful work output, and it is defined as the ratio of the real power (P) to the apparent power (S). The power factor is equal to 1 when all the power supplied by the source is being used effectively, which occurs under specific conditions related to the components of the circuit.

In the context of electrical circuits, the total impedance (Z) can be thought of as the combination of resistance (R) and reactance (X). When the resistive part (R) of the circuit equals the total impedance (Z), it signifies that there is no reactive component (X) present to affect the current and voltage phase relationship. This condition indicates that the circuit is purely resistive, meaning current and voltage are in phase with one another.

When R equals Z, the circuit demonstrates a power factor of 1, indicating that the load is purely resistive and there is no reactive power (Q) in the circuit to dissipate. In practical terms, this means that the entire power consumed is being converted into useful work without any losses associated with reactance.

Therefore, the scenario where resistance equals impedance is the defining condition for achieving a power factor of