What opposes current flow in a conductor carrying alternating current?

In the context of a conductor carrying alternating current, the factor that opposes current flow is known as impedance. Impedance is a complex quantity that incorporates both resistance and reactance, and it describes how an alternating current circuit resists the flow of electricity.

Resistance is the opposition to current flow due to collisions between charge carriers and the lattice structure of the conductor, while reactance arises from the effects of inductors and capacitors in the circuit, which can store and release energy. The total impedance takes both of these effects into account, which is crucial for accurately analyzing AC circuits.

Induced voltage refers to the voltage generated in a conductor due to a change in magnetic fields (according to Faraday's Law), but it doesn’t directly oppose current flow in the same way that impedance does. Direct current does not oppose alternating current; rather, it is a form of current that flows in one direction, unlike alternating current which changes direction periodically. Frequency relates to how fast the AC signal oscillates, but it alone does not define the opposition to current flow.

Thus, impedance is the correct concept when discussing what opposes current flow in an alternating current scenario.