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SESK: Stuff Everyone Should Know · sesk.info/elec-power-factor-def

Power factor compares the real power in watts with what?

Power factor is real power over apparent power.

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  1. Volts times amps, the apparent power ✔
  2. The motor's nameplate horsepower
  3. The breaker's amp rating

Why: When voltage and current are out of step, you still draw amps but get fewer watts of useful power. A lower power factor means more current for the same real work.

Huh, didn't know that: In OpenStax terms, power factor is the cosine of the phase angle between voltage and current.

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Where do electricians go when their job is done? They go h-ohm.
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References

Answer: Volts times amps, the apparent power. When voltage and current are out of step, you still draw amps but get fewer watts of useful power. A lower power factor means more current for the same real work.

  1. OpenStax University Physics Vol. 2, 15.4 Power in an AC Circuit openstax.org/books/university-physics-volume-2/pages/15-4-power-in-an-ac-circuit
    is known as the power factor, which is the amount by which the power delivered in the circuit is less than the theoretical maximum
    Checked 2026-10-10.

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