Heating, Ventilation, and Air Conditioning (HVAC ) Electrical Practice Test

What happens to the direction of current in an AC circuit?

1. It remains constant

2. It alternates periodically

3. It increases steadily

4. It decreases gradually

The correct answer is: It alternates periodically

In an AC (Alternating Current) circuit, the direction of current alternates periodically. This means that the current flow changes its direction multiple times in a cycle. In standard household AC systems, for instance, the electricity typically oscillates at a frequency of 60 Hz in North America, meaning that the current changes direction 60 times per second. This characteristic is what distinguishes AC from DC (Direct Current), where the flow of current remains constant in one direction. The alternating nature of AC allows for more efficient transmission of electricity over distances and can be easily transformed to different voltage levels, which is advantageous for both distribution and use in various appliances. The other options describe behaviors that do not correlate with the nature of AC. A constant current, for instance, describes the behavior of direct current, while a steadily increasing or decreasing current would imply a constant voltage and not the oscillation found in AC systems.