How is direct current (DC) defined?

Direct current (DC) is defined as the flow of electric charge in a unidirectional manner. This means that the electric charge flows in a single direction without changing polarity over time. In practical terms, this type of current is typically supplied by batteries and certain power supplies, where the electrons flow consistently from a negative terminal to a positive terminal.

In contrast, the other definitions describe different types of electrical current. For instance, the flow of electric charge that reverses direction is characteristic of alternating current (AC), where charges periodically change direction. The alternating nature of AC means it varies in both direction and magnitude. Furthermore, the flow of charge that alternates in magnitude also pertains to AC, reinforcing its variability over time. Lastly, the flow of electric charge in response to an external magnetic field describes electromagnetic induction, which is a different process by which current can be generated rather than a direct description of current types like DC or AC.

Understanding DC as unidirectional is essential when discussing circuits and devices that operate on a steady flow of electric energy, as many electronic devices are designed to function with DC.