# true power

Active power (P) is the effectively consumed power. It differs from reactive power (Q) and apparent power (S) in that it relates to a resistive load and has no phase shift between voltage and current.

For an AC voltage, active power is calculated by multiplying the rms values of current and voltage. It is expressed in watts (W).

The power factor is calculated from the quotient of active power and apparent power. calculate. It is the quotient of active power (P) and apparent power (S).