Conventional current

Here is the one genuinely confusing thing in the chapter, and it is worth meeting head-on: the direction of the current is defined as the opposite of the way the electrons go.

The direction of an electric current

By convention, the direction of an electric current is taken as the direction opposite to the direction in which the electrons flow. So while electrons travel from the negative terminal to the positive one, a current is said to flow from the positive terminal to the negative.

What is moving	Which way it goes
The electrons themselves	Negative terminal to positive terminal
The conventional current	Positive terminal to negative terminal

Figure to be added

Figure 19.8 — an electric current flowing through a conductor: fixed metal ions, the free electron current arrowed one way, and the conventional current arrowed the opposite way.

Figure to be added

Figure 19.9 — a bulb wired to a battery, with one arrow labelled as the direction of the conventional current and another, pointing the other way, labelled as the direction of the electron current.

Both arrows describe the same circuit

Nothing is happening twice. There is one flow of electrons, and two ways of labelling its direction. The convention was fixed before anyone knew that electrons were the things that moved, and it was kept because every formula and every circuit diagram in use already depended on it.

In this course, “current” means the conventional one

Unless a question says electron current, the arrow it wants is the conventional one: out of the positive terminal, round the circuit, back into the negative.

Current: plus to minus. Electrons: minus to plus

The conventional current runs from + to −. The electrons run from − to +. They are the same event described with opposite arrows.