What is reactive power?

Reactive power is a crucial aspect of alternating current (AC) electrical systems, primarily associated with the behavior of inductive and capacitive components. In AC circuits, inductors (like motors and transformers) and capacitors store energy in magnetic and electric fields, respectively. This energy flow does not result in actual power that does work in the conventional sense (like turning a motor), hence it is termed "reactive power."

While real power (measured in watts) is the power that performs useful work, reactive power (measured in volt-amperes reactive, or VAR) oscillates between the source and reactive components without being consumed. It’s necessary for maintaining the voltage levels that enable active power to do useful work in an electrical system. Understanding reactive power is essential, especially in the context of power factor, which measures how effectively the power is being utilized in a circuit.

The other choices address different aspects of electrical power. For instance, power consumed by resistive loads pertains to real power, and the mention of total power available in an AC circuit conflates real and reactive power into apparent power. The reference to power converting to heat specifically connects to resistive loads, again focusing on real power rather than the nature of reactive power itself.