Which unit expresses apparent power?

Which unit expresses apparent power?

• A. Volt-amps reactive (VAR)
• B. Watt (W)
• C. Joule (J)
• D. Volt-amps (VA)

Answer: (D)

Apparent power is the total power flow in an AC circuit, represented by S, the magnitude of the complex power P + jQ. It equals the product of RMS voltage and RMS current: S = V_rms × I_rms. Because it comes from volts multiplied by amps, its unit is volt-amps (VA). Real power, measured in watts, is P = V_rms I_rms cos φ and represents the actual useful work. Reactive power is Q = V_rms I_rms sin φ and is measured in volt-amps reactive (VAR), reflecting energy stored and returned each cycle. Joule is a unit of energy, not power. So apparent power uses VA.

Apparent power is the total power flow in an AC circuit, represented by S, the magnitude of the complex power P + jQ. It equals the product of RMS voltage and RMS current: S = V_rms × I_rms. Because it comes from volts multiplied by amps, its unit is volt-amps (VA). Real power, measured in watts, is P = V_rms I_rms cos φ and represents the actual useful work. Reactive power is Q = V_rms I_rms sin φ and is measured in volt-amps reactive (VAR), reflecting energy stored and returned each cycle. Joule is a unit of energy, not power. So apparent power uses VA.