BASIC
NEC 2023
AC Power & Power Factor Practice Test
Free online AC power and power factor practice test. 25 basic electrical questions on real power, reactive power, apparent power, the power triangle, and power factor correction. Good for electrician exam prep.
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AC circuits deal with three kinds of power. Real power (watts, W) does actual work — heat, light, motion. Reactive power (VARs) is power that inductors and capacitors trade back and forth without doing useful work. Apparent power (volt-amps, VA) is the total the source supplies: S = V × I. Power factor (PF = P / S) tells you how much of that apparent power is actually useful. Motors and other inductive loads pull power factor down ("lagging"); capacitors can push it back up. A low power factor means more current for the same useful work — bigger wires, bigger bills.
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