Nate Electrical Practice Exam 2026 - Free Electrical Practice Questions and Study Guide

Alternating current (AC) is characterized by the fact that it reverses direction periodically. This change in direction is a fundamental aspect of how AC operates, differentiating it from direct current (DC), which flows in a single, constant direction. In AC systems, the voltage and current follow a sine wave or another waveform that periodically shifts from positive to negative values, typically at a frequency of 60 Hertz in many regions. This allows for the efficient transmission of electrical power over long distances and enables the use of transformers to step voltage levels up or down as needed for various applications.

The other characteristics listed do not correctly describe AC. For example, AC does not have a constant voltage, as its voltage varies over time. It also cannot be stored in batteries in its original form since batteries typically use DC. Lastly, the statement about it flowing in one direction pertains specifically to DC, not AC, which is defined by its ability to reverse direction.