When an alternating or AC voltage is applied across an inductor the flow of current through it behaves very differently to that of an applied DC voltage. The effect of a sinusoidal supply produces a phase difference between the voltage and the current waveforms. In an AC circuit, the opposition to current flow through an inductors coil windings not only depends upon the inductance of the coil but also the frequency of the AC waveform.
The opposition to current flowing through the coil in an AC circuit is determined by the AC resistance, more commonly known as Impedance (Z), of the circuit.
As the component we are interested in is an inductor,
the reactance of an inductor is therefore called "Inductive Reactance".
In other words, an inductors electrical resistance when used in an AC circuit is called Inductive Reactance.
Inductive Reactance which is given the symbol XL, and is the property in an AC circuit which opposes the change in the current. In an AC inductive circuit, this capacitive reactance value, XL is equal to 2πƒL or jωC L.
What is AC Inductance?
In a pure AC Inductive circuit, the voltage and current are both “out-of-phase” with the current lagging the applied voltage by 900 (or π/2 rads). So for a purely inductive AC circuit, VL “leads” IL by 900, or we can say that IL “lags” VL by 900.