What type of current is characterized by a flow that varies in direction?

The type of current characterized by a flow that varies in direction is alternating current (AC). AC is called "alternating" because the flow of electric charge periodically reverses direction. This is commonly used in power supplies for homes and businesses because it is efficient for transmitting electricity over long distances. The frequency of the direction changes in AC is typically measured in hertz (Hz), indicating how many cycles occur in one second.

In contrast, direct current (DC) flows in a single direction consistently and is typically used in battery-operated devices. Digital current and signal current are terms that can refer to specific types of electrical signals in communication and data systems, but they do not specifically describe current variation in direction in the way that AC does. Understanding the nature of AC is crucial for various applications in electrical engineering, from residential wiring to telecommunications.