Before revision: General caseSchematic showing how power factor is calculatedThe general expression for power factor is given by where is the real power measured by an ideal wattmeter, is the rms current measured by an ideal ammeter, and is the rms voltage measured by an ideal voltmeter.
After revision: where is the real power measured by an ideal wattmeter, is the rms current measured by an ideal ammeter, and is the rms voltage measured by an ideal voltmeter.