Which formula is used to calculate power in an AC circuit?

The formula used to calculate power in an AC circuit is P = V × I × cos(θ). This equation incorporates the voltage (V), current (I), and the power factor (cos(θ)), which accounts for the phase difference between the voltage and current in an alternating current (AC) circuit.

In AC circuits, not all the power supplied by the source is used for useful work due to this phase difference, represented by the angle θ. The power factor (cos(θ)) indicates how effectively the current is being converted into useful work; it varies between 0 and 1, with a value of 1 indicating that all the power is being effectively used.

This relationship is critical for understanding the concept of real power (measured in watts), which is the actual power consumed by the load. Conversely, other formulas presented do not accurately represent the calculation of power in AC circuits.