What is the primary difference between AC and DC current?

The primary difference between AC (Alternating Current) and DC (Direct Current) is that AC cycles in direction, while DC flows in one direction only. This distinction is fundamental to understanding how each type of current behaves in electrical systems.

In AC, the flow of electric charge periodically reverses direction, which means the voltage also alternates in polarity. This cycling allows AC to be transmitted over long distances more efficiently and is the reason why it is predominantly used in household power supply systems.

On the other hand, DC maintains a constant voltage and current flow in a single direction, making it suitable for powering electronic devices, batteries, and certain types of motors. The unidirectional flow of DC simplifies certain applications, such as in circuits where consistent voltage is necessary.

Understanding this difference is crucial for grasping the basic principles of electrical engineering and the different usages of electricity in everyday applications. Options discussing AC and DC in terms of outlets or batteries, and voltage comparisons, don't capture the essential characteristic that defines these currents.