What is 'reactive power' in the context of electrical circuits?

Reactive power refers to the power that oscillates between the source and the load in an alternating current (AC) circuit without contributing to any work output. This type of power is associated with the energy storage in inductors and capacitors. In an AC system, particularly in circuits with inductive or capacitive loads, reactive power is essential for maintaining the voltage levels necessary for the system's operation.

While active power (or real power) is responsible for performing actual work, such as lighting a bulb or driving a motor, reactive power does not perform work but is crucial for sustaining electric fields in inductive loads and electric fields in capacitors. This interplay between reactive power and these components allows for the efficient transfer of electrical energy in AC circuits.

The essential role of reactive power becomes evident in applications such as electric power transmission, where it helps in voltage regulation and maintaining the stability of the power system. Thus, the characterization of reactive power as oscillating between the source and load without doing work accurately reflects its function in electrical circuits.