What describes alternating current (AC)?

Alternating current (AC) is characterized by its ability to change direction periodically. This means that the flow of electric charge reverses its direction at specific intervals, creating a waveform that typically resembles a sine wave. AC is predominant in household and industrial power systems because it allows for the efficient transmission of electricity over long distances and facilitates the operation of motors and transformers.

While some forms of current flow in only one direction, that description applies to direct current (DC) rather than AC. The concept of current decreasing over time relates to specific scenarios in circuits but does not define the nature of AC as a current type. Similarly, current that is stored in capacitors refers to the static charge that can be retained in an electric field and is not a characteristic of AC itself. Therefore, the recognition that AC changes direction periodically reinforces its fundamental property and distinguishes it from other current types.