Breifly explain about reactive power in electric circuits?

Answer 1

Reactive power is opposite to Active power. The vector sum of these two powers is apprant power. So reactive power is vector difference between Apprant power & actual power given by

Reactive power= Root of (difference between squares of apprant & active power).

It is lost power of the system on which power factor depends.

Answer 2

'Reactive power', measured in reactive volt amperes (var), describes the rate at which energy is supplied to, and stored within, a circuit's magnetic and/or electric field(s) and, then, returned to the supply, during every half cycle of alternating current.

Contrast this with 'true power', measured in watts(W), which describes the rate at which energy is permanently expended overcoming a circuit's resistance or through doing work (e.g. by an electric motor delivering energy to its mechanical load).

Reactive power is sometimes described as 'wasted power'; this is a complete misconception, because reactive power is essential, as it is required to establish and maintain a circuit's magnetic and/or electric fields.

The combination (vectorial sum) of true power and reactive power, is called 'apparent power', measured in volt amperes (V.A).

The true power of a circuit is measured using a wattmeter, while apparent power is simply the product of the supply voltage and the load current.