Multi-Craft Maintenance Practice Test

Total opposition to current flow in an AC circuit is expressed as impedance. Impedance combines both resistance and reactance, accounting for the effects of both the resistive components (which dissipate energy) and the reactive components (which store and release energy) in the circuit.

In an AC circuit, resistance refers to the opposition to current flow due to resistive elements, while reactance refers specifically to the opposition due to inductors and capacitors, which depend on the frequency of the AC signal. Impedance includes both these factors, measured in ohms, and provides a comprehensive understanding of how the circuit will respond to an alternating current. This is crucial for calculating how much current will flow when a particular AC voltage is applied, integrating the effects of all components within the circuit.