What is a key characteristic of alternating current (AC)?

A key characteristic of alternating current (AC) is that electrons alternately reverse direction. This means that the flow of electric charge changes its direction periodically, which contrasts with direct current (DC), where the flow of electric charge remains constant and unidirectional. AC is commonly used in household power supplies because its ability to change direction allows it to be easily transformed to different voltage levels, making it efficient for long-distance transmission of electricity.

The behavior of AC is defined by its frequency, typically measured in hertz (Hz), which indicates how many times per second the direction of the current reverses. This characteristic is fundamental in the design of electrical systems and devices, which can operate effectively using AC due to these properties.