Which unit is used to measure real power in an AC circuit?

Which unit is used to measure real power in an AC circuit?

• A. Volt-amperes (VA)
• B. Watts (W)
• C. Volt-amperes reactive (VAR)
• D. Amperes (A)

Answer: (B)

Real power in an AC circuit is measured in watts (W). This measurement represents the actual power consumed by the circuit to perform useful work, such as lighting a bulb or running a motor. In alternating current systems, real power takes into account the phase angle between the current and voltage waveforms. It is the product of the voltage, current, and the cosine of the phase angle (the power factor). Thus, watts accurately reflect how much energy is actually being utilized to accomplish electrical work over time. The other units mentioned measure different types of power or electrical quantities. For instance, volt-amperes (VA) indicate apparent power, which accounts for both real power and reactive power, but doesn’t reflect the actual consumption of the circuit. Volt-amperes reactive (VAR) measures reactive power, which is important in AC circuits for managing inductive and capacitive loads but does not contribute to work done. Amperes (A) refer to the flow of electric current and do not quantify power directly without considering voltage.

Real power in an AC circuit is measured in watts (W). This measurement represents the actual power consumed by the circuit to perform useful work, such as lighting a bulb or running a motor.

In alternating current systems, real power takes into account the phase angle between the current and voltage waveforms. It is the product of the voltage, current, and the cosine of the phase angle (the power factor). Thus, watts accurately reflect how much energy is actually being utilized to accomplish electrical work over time.

The other units mentioned measure different types of power or electrical quantities. For instance, volt-amperes (VA) indicate apparent power, which accounts for both real power and reactive power, but doesn’t reflect the actual consumption of the circuit. Volt-amperes reactive (VAR) measures reactive power, which is important in AC circuits for managing inductive and capacitive loads but does not contribute to work done. Amperes (A) refer to the flow of electric current and do not quantify power directly without considering voltage.