True power in an AC circuit is measured in which unit?

True power in an AC circuit is measured in which unit?

• A. Watts
• B. Volt-Amps
• C. VAR
• D. Joules

Answer: (A)

Real power in an AC circuit is the actual rate at which energy is converted to useful work in the load. It is measured in watts, reflecting the portion of power that does work as the voltage and current waveforms have a phase relationship. The formula P = VI cosφ shows how the cosine of the phase angle reduces the product VI to the true power that can be delivered. The volt-ampere unit (VA) represents apparent power, which is VI without accounting for phase angle and includes power that isn’t doing work. Reactive power, measured in VAR, accounts for energy stored and returned by reactive elements like inductors and capacitors. Joules are units of energy, not power, so they don’t represent the rate of energy transfer.

Real power in an AC circuit is the actual rate at which energy is converted to useful work in the load. It is measured in watts, reflecting the portion of power that does work as the voltage and current waveforms have a phase relationship. The formula P = VI cosφ shows how the cosine of the phase angle reduces the product VI to the true power that can be delivered. The volt-ampere unit (VA) represents apparent power, which is VI without accounting for phase angle and includes power that isn’t doing work. Reactive power, measured in VAR, accounts for energy stored and returned by reactive elements like inductors and capacitors. Joules are units of energy, not power, so they don’t represent the rate of energy transfer.