In the Sparkfun transistor tutorial[1] there is the following line:
“The NPN transistor is designed to pass electrons from the emitter to the collector (so conventional current flows from collector to emitter).”
What does this mean? I thought electricity just was the flow of electrons, so how can electrons be flowing in one direction while current is flowing in the other?
Also, where should questions of this sort go? I don’t see any “theoretical” threads.
There are two ways to look at current flow. They are commonly referred to as electron current flow and conventional current flow. Conventional flow is also sometimes referred to as hole flow, with the “holes” being the absence of electrons. It doesn’t really matter which way you look at a circuit, as long as you are consistent. The math works either way. The signs in the equation will be opposite, but the answer will be the same. The school I went to taught electron flow, so that is what I tend to use. Conventional flow has the advantage of current flowing in the direction of the arrows on diodes and transistors.
Thank you!
Doing KVL equations might trip you up if you don’t get the current flow the right direction. I was also taught electron flow, with a quick lesson on hole flow. Think of it this way, as an electron moves to a hole, it leaves a hole behind it. While the electron moves one direction, the hole moves the opposite.