Conventional vs Electron Flow

Quick Answer

Conventional current flows from the positive terminal through the external circuit to the negative one. In a metal the charge carriers are electrons, which drift the opposite way. Both descriptions give identical currents, voltages and powers, so schematics, datasheets and every equation on this site keep the conventional direction and nothing needs correcting.

Benjamin Franklin fixed the sign convention well over a century before anyone knew what a charge carrier was, and he had no way to tell which of the two things he was labelling actually moved. In metals it turned out to be the negative one. By then the convention was in every textbook, every drawing and every equation, and revising it would have bought nothing — current is a signed quantity, and a negative charge moving left counts as a positive current moving right. The arithmetic does not care which picture you hold.

So the working rule is short. Draw and calculate in conventional current, from plus, through the external circuit, to minus, exactly as electric current does throughout. Electron flow describes what happens inside the copper: useful when the physics of the material is the subject, irrelevant when the answer wanted is a voltage or a power.

Carrier sign does become physical in a few places. A Hall voltage reverses with it, which is how the sign of a semiconductor's majority carrier is measured. Electrolytes and plasmas carry both signs at once, moving in opposite directions, and both contribute to the same current.