If the load driven by an alternator is purely inductive, how does the current behave in relation to the potential difference?

In an alternating current (AC) circuit where the load is purely inductive, the current lags behind the potential difference (voltage) across the inductor. This phase difference occurs because, in an inductive load, the inductor stores energy in the form of a magnetic field. When the voltage across the inductor rises, it takes some time for the current to increase due to the inductor's opposition to changes in current (a phenomenon known as inductive reactance).

The concept of phase angle is crucial in understanding this relationship. In purely inductive circuits, the current can be represented as a sine wave that achieves its maximum value after the voltage sine wave reaches its maximum. Typically, this phase difference is 90 degrees, which indicates that peak voltage occurs one-quarter of a cycle before peak current.

In this way, the behavior of current in relation to the potential difference in a purely inductive load demonstrates that the current consistently lags, reinforcing the characteristics of inductors in AC circuits.