Inductor quirks

Inductor quirks

In an ideal case, an inductor acts as a purely reactive device. That is, its opposition to AC current is strictly based on inductive reaction to changes in current, and not electron friction as is the case with resistive components. However, inductors are not quite so pure in their reactive behavior. To begin with, they’re made of wire, and we know that all wire possesses some measurable amount of resistance (unless its superconducting wire). This built-in resistance acts as though it were connected in series with the perfect inductance of the coil, like this:

Consequently, the impedance of any real inductor will always be a complex combination of resistance and inductive reactance. Compounding this problem is something called the skin effect, which is AC’s tendency to
flow through the outer areas of a conductor’s cross-section rather than through the middle.