How is true power computed in a circuit where AC voltage and current are out of phase?

True power in an AC circuit, especially where the voltage and current are out of phase, is determined by the relation between apparent power and the power factor. Apparent power is the product of the root mean square (RMS) voltage and RMS current, which gives you the total power in the circuit without considering the phase difference. However, to find true power (also known as real power), you must account for how much of that power is actually being used to do work, which is influenced by the phase difference.

The power factor is defined as the cosine of the phase angle between voltage and current. It represents the fraction of the total power that is actually doing useful work. To compute the true power in the circuit, multiplying the apparent power by the power factor is necessary. This calculation gives you the real power consumed by the circuit, which is what you want when considering power used by devices connected to the circuit.

Understanding this concept is crucial, as it allows engineers and technicians to assess how efficiently power is being used in AC systems, particularly in cases where there is a significant phase difference between voltage and current.