What is the power factor in AC circuits?

The power factor in AC circuits is defined as the ratio of real power, measured in watts, to apparent power, measured in volt-amperes. This ratio reflects how effectively electrical energy is being converted into useful work output. A power factor of 1 (or 100%) indicates that all the power supplied by the source is being used effectively for work, while a power factor less than 1 signifies that some portion of the power is simply circulating in the circuit and not contributing to output.

In practical terms, power factor is crucial for understanding the efficiency of an electrical system. A low power factor can lead to increased costs and reduced capacity in electrical systems because it implies that not all the power supplied is being used efficiently. Therefore, optimizing power factor is important for both energy efficiency and cost management in AC circuits.