power factor

In alternating-current (AC) circuits, the power factor is a measure of how effectively electrical power is being used. It is defined as the ratio of the mean actual power (in watts) to the apparent power (in volt-amperes). This ratio is equal to the cosine of the phase difference between the electromotive force (voltage) and the current.1

In an AC circuit, the current and voltage may not be perfectly in sync, meaning they don't reach their maximum or minimum values at the exact same time. This phase difference, represented by the angle (\phi), affects the power factor. A power factor of 1 (or 100%) indicates that all the power supplied is being used effectively for work. A power factor less than 1 means that some power is lost or returned to the source, often due to reactive components like inductors and capacitors. The power factor is crucial for evaluating the efficiency of electrical systems.23