Which of the following best describes direct current (DC)?

Direct current (DC) is characterized by the flow of electric charge in a single, constant direction. This means that the electrons move steadily from the negative terminal to the positive terminal, resulting in a unidirectional current. The consistency of this flow makes DC particularly suitable for various applications, such as in batteries, electronic devices, and circuits where stable and predictable power supply is essential.

In contrast, alternatives involving alternating flow, rotation, or polarity changes do not accurately reflect the nature of direct current. These characteristics are more aligned with alternating current (AC), where electrons oscillate back and forth, changing direction periodically. Understanding this fundamental distinction is crucial for anyone studying electrical principles in the context of fire investigation and safety.