Inductive reactance is an opposition to the change of current on an inductive element. Inductive reactance is proportional to the sinusoidal signal frequency and the inductance .
The average current flowing in an inductance in series with a sinusoidal AC voltage source of RMS amplitude and frequency is equal to:
The average current flowing in an inductance in series with a square wave AC voltage source of RMS amplitude and frequency is equal to:
- making it appear as if the inductive reactance to a square wave was
An inductor consists of a coiled conductor. Faraday's law of electromagnetic induction gives the counter-emf (voltage opposing current) due to a rate-of-change of magnetic flux density through a current loop.
For an inductor consisting of a coil with loops this gives.
The counter-emf is the source of the opposition to current flow. A constant direct current has a zero rate-of-change, and sees an inductor as a short-circuit (it is typically made from a material with a low resistivity). An alternating current has a time-averaged rate-of-change that is proportional to frequency, this causes the increase in inductive reactance with frequency.
Read more about this topic: Electrical Reactance