What is the main difference between alternating current (AC) and direct current (DC)?

The primary distinction between alternating current (AC) and direct current (DC) lies in the nature of the current flow. In the case of AC, the current changes direction periodically, which means that it cycles back and forth within a circuit. This characteristic allows AC to efficiently travel long distances, making it the preferred choice for power distribution in homes and commercial buildings.

The option surrounding AC consistently flowing in one direction refers to direct current instead, which maintains a constant directional flow, highlighting a fundamental difference from AC. While it is true that AC can often operate at higher voltages for transmission purposes, this doesn't define the core difference between the two types of current. Furthermore, the statement about AC being used solely in residential wiring is inaccurate, as AC is widely used in various applications, including industrial and commercial sectors, and not limited to residential environments. Understanding the periodic change in direction of AC is crucial for differentiating it from DC and recognizing its application in power systems.