Direction in which an electric current is considered to flow in a circuit. By convention, the direction is that in which positive-charge carriers would flow from the positive terminal of a cell to its negative terminal. It is opposite in direction to the flow of electrons. In circuit diagrams, the arrows shown on symbols for components such as diodes and transistors point in the direction of conventional current flow.
In the 19th century, with the early applications of electricity such as starter motors and light bulbs, there was not an exact understanding of the nature of current flow. It was assumed at the time that electricity flowed from the positive terminal to the negative.
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