Oscilloscopes measure current and voltage and, through the magic of mathematics, calculate power. Unfortunately, power comes in a large number of guises: instantaneous, real, apparent, and reactive.

Power factor (pf) is the ratio between real power (P) flowing to the load, and the apparent power (S) in the circuit: pf = P/S. It is a sinusoidal waveform and therefore expressed as a dimensionless ...