In electrical theory, what does the term "impedance" refer to?

Impedance refers to the total opposition that a circuit presents to the flow of alternating current (AC). It encompasses not only resistance but also the effects of inductance and capacitance in the circuit. This means that impedance is a complex quantity that can affect how current flows, how voltage is distributed, and how power is consumed in AC systems.

Impedance is measured in ohms and is represented in a complex form, typically written as a combination of a real part (resistance) and an imaginary part (reactance). As a result, it influences the phase relationship between voltage and current, which is crucial in the operation of AC circuits.

In contrast, the other options describe different electrical concepts: joining conductors refers to electrical connections, storage of electrical charge pertains to capacitors, and flow of electrical energy describes power transmission, none of which adequately capture the specific opposition to current flow characteristic of impedance in AC circuits.