2.01 Electron Flow and Conventional Current.

After completing this section you should be able to:

Electron Flow

Why do the electrons move?

The electrons are repelled by the negative charge, at the negative terminal of the battery and are attracted by the positive charge, at the positive terminal. Therefore, the electrons drift away from the negative terminal and towards the positive terminal. When the electrons reach the positive terminal, a chemical reaction transfers them across the battery and back to the negative terminal.

Compare the electrons moving through the cct., to ball bearings rolling down a ramp and the battery to a lift, which raises the ball bearings back to the top of the ramp, each time they reach the bottom.

Conventional current flow.

As stated above, the movement of electrons (and therefore the direction of TRUE current flow), is from the negative terminal of the battery, to the positive terminal. However, before the true nature of electricity was known, scientists assumed that current was the result of the movement of positively charged particles and therefore that current flowed from the positive to the negative terminal. This (incorrect) convention is still used today and is called conventional current flow. When discussing the true nature of current, we will refer to electron flow. In general, conventional current flow is used in circuit diagrams and true electron flow is used, when we describe how an individual component works.