CompTIA Network+ Practice Test

What is the primary characteristic of Alternating Current (AC)?

1. Current moves in one direction

2. Current constantly reverses direction

3. Provides constant voltage

4. Used exclusively in data centers

The correct answer is: Current constantly reverses direction

The primary characteristic of Alternating Current (AC) is that the current constantly reverses direction. This means that the flow of electric charge periodically changes its direction, which is a fundamental property of AC. Unlike Direct Current (DC), where the electric charge flows in a single constant direction, AC is typically represented by a sinusoidal wave, indicating that the voltage and current vary in magnitude and direction over time. This characteristic enables AC to be more efficient for power distribution over long distances, as it can easily be transformed to higher or lower voltage levels using transformers. This ability to change voltage makes AC suitable for residential and commercial power systems, while DC is often used in applications that require stable and constant voltage. In contrast, the other options imply characteristics that are not true for AC or are specific to other types of electrical current or systems. For instance, the description of a current moving in one direction pertains specifically to DC. Providing constant voltage is also a feature more associated with DC current rather than the fluctuating nature of AC. Lastly, while AC is widely used, including in data centers, it is not exclusive to them, as AC power supplies most of the electricity in household and industrial applications.