CBSE Class 12-science Answered

In an a.c. (alternating current) circuit, there are two components to impedance. There is a resistive component and a reactive component. The reactive component is the algebraic sum of the total inductive and capacitive reactances. Both the resistive and reactive components impede the flow of a.c. current. The resistive component converts power into heat that is wasted. The reactive component stores power in a magnetic field (for inductors) and an electric field (for capacitors). When the power source is turned off, the magnetic and electric fields collapse and return the stored energy back to the circuit in the form of an induced current. So no energy is wasted in the reactive components. Therefore since power is measured in watts, the current flowing through reactive components is considered to be "wattless current".