What is alternating current?

Alternating current (AC) is defined as a flow of electric charge that regularly reverses its direction. This characteristic is fundamental to the operation of many electrical systems and is distinguished from direct current (DC), where the flow of electric charge moves in one consistent direction.

The regular reversal in AC can be represented graphically by a sine wave, showing its periodic nature. This property allows AC to be transmitted over long distances more efficiently compared to DC, as it can be easily transformed to higher or lower voltages using transformers. This makes it the preferred choice for power distribution networks and household electricity.

The other options describe different types of electrical current but do not adequately represent alternating current. While a uniform flow of electricity suggests a steady and unchanging current, which applies to direct current, it does not capture the essence of AC. The mention of batteries is misleading as they primarily produce direct current, and current that does not vary aligns more closely with direct current as well. The unique characteristic of alternating current is its ability to reverse direction, making the first choice the correct one.