What is impedance?

Impedance is defined as the opposition to alternating current (AC) in an electrical circuit. It encompasses not only resistance (the opposition that resistors present to current) but also includes reactance, which is the opposition that capacitors and inductors present due to their ability to store energy in electric and magnetic fields, respectively. This means that impedance is a broader concept than simply resistance to direct current (DC).

In AC circuits, impedance is a complex quantity that can be represented as a combination of resistive and reactive components, emphasizing that it affects the magnitude and phase of the current flowing through the circuit. Therefore, the correct understanding of what impedance entails is vital for analyzing and designing AC circuits effectively, making it clear that the opposition to AC is the defining feature of impedance.