In AC circuits, what is the total opposition to current flow called?

In AC circuits, the total opposition to current flow is referred to as impedance. Impedance is a comprehensive measure that encompasses not only the resistance but also the reactance, which is the opposition to the flow of alternating current due to inductance and capacitance. This makes impedance a more accurate term in the context of AC circuits compared to resistance, which only accounts for the resistive component of that opposition.

Impedance is particularly important in AC systems because it helps to predict how current behaves when subjected to varying frequencies and phase shifts, which is a significant aspect of AC circuit analysis. It is typically expressed in ohms, similar to resistance, but the calculations might involve complex numbers due to the phase differences between voltage and current.

In contrast, while resistance measures the opposition to current flow in both AC and DC systems, it does not account for the effects of reactance found in AC circuits. Other terms, such as voltage drop, refer to the loss of voltage as current flows through resistive components but do not represent total opposition to flow like impedance does. Current, on the other hand, simply describes the flow of electric charge and is unrelated to the total opposition experienced by that flow.