What is the unit of reactive power in an electric circuit?

The unit of reactive power in an electric circuit is expressed as "Var," which stands for volt-ampere reactive. Reactive power is associated with the energy that oscillates between the source and the reactive components of the circuit, such as inductors and capacitors. Unlike active power (measured in watts), which does work in an electrical system, reactive power does not perform any real work but is essential for maintaining voltage levels necessary for active power to be transmitted effectively. Thus, the "Var" unit specifically quantifies this alternating current component and distinguishes it from other electrical quantities.

The other units listed do not appropriately represent reactive power: Watts measure active power, Voltamperes measure apparent power (which combines both active and reactive power), and Joules measure energy, not power. Each of these units pertain to different aspects of electrical systems and therefore do not apply to the unit of reactive power.