How is the direction of current flow in a circuit usually defined?

The direction of current flow in a circuit is conventionally defined as flowing from positive to negative. This definition stems from the historical context of electric current, where it was initially thought that electric charge flowed from positive terminals to negative ones. This convention has stuck and is integral to understanding circuit diagrams and the analysis of electrical circuits.

In a direct current (DC) circuit, the positive terminal is associated with a higher electric potential, while the negative terminal is at a lower potential. Therefore, when electrons move from the negative terminal (where they are in excess) towards the positive terminal, the conventional current is represented as flowing in the opposite direction—from the positive to the negative terminal. This convention simplifies the design and analysis of electrical systems, allowing engineers and technicians to communicate effectively about circuit behavior and operation. Understanding this flow is crucial when working with circuit elements and troubleshooting electrical systems.