Which of the following is NOT a feature of direct current?

Direct current (DC) is characterized by a constant voltage that maintains a steady direction of flow. This means that the electrical charge moves in one direction only, which is referred to as unidirectional flow. This characteristic makes DC ideal for applications that require stable and predictable performance, such as powering electronic devices, batteries, and certain types of motors.

The key feature of DC is its ability to maintain a constant voltage over time, and it flows steadily without fluctuations, unlike alternating current (AC), which varies in voltage and can flow in both directions. Therefore, the statement about variable flow is not a feature of direct current, as DC has a consistent and steady flow. This distinction is fundamental in understanding the properties of current types and their respective applications in electrical systems.