In an AC circuit, what primarily causes the phase difference between voltage and current?

In an AC circuit, inductance primarily causes the phase difference between voltage and current. When an inductor is introduced into an AC circuit, it creates a magnetic field that opposes changes in current. This property results in a delay of the current wave relative to the voltage wave. Essentially, as the AC voltage increases, the inductor produces a back electromotive force (EMF) that prevents the current from reaching its maximum value simultaneously. This leads to a situation where the current lags the voltage.

While other components like capacitance and resistance also play roles in AC circuits, it is the inductance that is specifically responsible for the noticeable lag in phase, which is a hallmark of inductive circuits. In a purely resistive circuit, the voltage and current are in phase, whereas in circuits with inductive reactance, the phase difference becomes significant. Thus, understanding that inductance is the primary cause gives insight into AC circuit behavior and the relationship between voltage and current over time.