Question

The unit of reactive power is

• A. Watt
• B. Ampere
• C. Volt
• D. VAR

Hint:

Remember the power triangle:
Active Power ($P$) $\rightarrow$ Watts (W)
Reactive Power ($Q$) $\rightarrow$ Volt-Amperes Reactive (VAR)
Apparent Power ($S$) $\rightarrow$ Volt-Amperes (VA)

Answer 1

The Correct Option is D

Step 1: Understanding the Question:
This is a conceptual question related to AC power analysis.
It asks for the specific standard unit of measurement used for reactive power.

Step 2: Key Formula or Approach:
In AC circuit theory, complex power $S$ is composed of two distinct components:
\[ S = P + jQ \]
where $P$ is the real (active) power, and $Q$ is the reactive power.

Step 3: Detailed Explanation:

• Active Power ($P$): Represents the actual power dissipated by resistive elements. Its unit is the Watt.

• Reactive Power ($Q$): Represents the power that oscillates back and forth between the source and the reactive elements (inductors and capacitors). Its unit is the Volt-Ampere Reactive (VAR).

• Apparent Power ($|S|$): The overall magnitude of complex power, which is measured in Volt-Amperes (VA).

• Volt is the unit of electric potential, and Ampere is the unit of electric current.

Step 4: Final Answer:
The correct unit for reactive power is VAR, which corresponds to Option (D).