Final answer:
The opposition offered by a coil to the flow of alternating current, disregarding resistance, is called inductive reactance. Inductive reactance, combined with resistance and capacitive reactance, defines impedance in AC circuits.
Step-by-step explanation:
The opposition offered by a coil to the flow of alternating current (AC), disregarding resistance, is called inductive reactance. This effect occurs because an inductor opposes any change in the current flowing through it. The measure of this opposition is analogous to resistance in a DC circuit, but for an AC circuit where the current and voltage may not be in phase, this effect is combined with resistance and capacitive reactance to define impedance, which is the AC analogue to resistance. Inductive reactance is denoted by XL and is measured in ohms, increasing directly as the frequency of the AC source increases.
Ohm's law for an inductor, which relates the voltage across the inductor (V) to the current through the inductor (I), can be expressed in terms of inductive reactance. This relationship highlights that inductive reactance is a significant factor in limiting the flow of AC current within a circuit that includes an inductor.