In electrical terms, what does 'impedance' encompass?

Impedance is a comprehensive concept in electrical engineering that describes the total opposition to the flow of alternating current (AC) in a circuit. It is not limited to just resistance, which is the opposition to current flow in a purely resistive circuit. Instead, impedance includes both resistance and reactance.

Reactance arises from the effects of inductors and capacitors in the circuit, which introduce frequency-dependent behavior. Inductive reactance opposes changes in current, while capacitive reactance opposes changes in voltage. These two components work in conjunction with resistance to determine how much current will flow in response to a given voltage.

Thus, impedance accurately represents the complete opposition to AC flow, factoring in both the resistive and reactive elements of the circuit. This is essential for understanding AC circuits, as it helps in calculating how circuits behave when subjected to alternating voltages.