Current direction

Question

Why are advanced electrical engineers still being taught that current flows from positive to negative? This erroneous idea is often referred to as 'conventional current'.

In a simple circuit with a battery and a loop of copper wire connecting the terminals, absolutely nothing is moving in the positive to negative direction, yet many engineers will say 'well yes, the electrons move in that direction but not the current.' (Heck, even the 'hole flow' in semiconductors is misleading, to create a new hole an electron has to move, a hole does not exist therefore it cannot move!)

This situation makes it very hard for us who learned basic electronics in high school to learn from the college grads who see electricity as though they were viewing it through a mirror.

Edited addition: I would like to comment on some of the responses. " it's a rant", Yes it is. I would hoping some influential university professor would stumble across this and suggest a change though the powers to be, to get everyone teaching on the same page. "Current is charges flowing, not necessarily electrons. In a solution, current can be the physical movement of positive ions, for example".

I will agree that in a solution the whole atom can move, but in dry electrical circuits the atoms themselves do not move. (as far as I know.) "charged particles move". Okay, if the atom itself is not moving what part of the atom moves to change it's charge? Only the electron can move in and out of the atom. A moving 'charge' is caused by an electron moving somewhere. "conceptual current" Think about that name, it is not named "real current".

BTW, I am not here to irritate my well educated friends, I just wish they would agree that all levels of educational instruction should teach current flow the same way, (hopefully the correct way.)

Just to complicate your simplistic view a little bit, see the discussion here, for example: https://www.physicsforums.com/threads/why-do-holes-not-contribute-to-conduction-in-metals.814178/ — jonk, Feb 19 '17 at 05:31
Advanced engineers know what is flowing and which way it is flowing. Most of the time, though, it actually doesn't matter. Certainly in circuit analysis, you don't need to think about electrons at all. And you shouldn't be thinking about them. If you dig into semi-conductor device characteristics, you may need to give some thought to charge carrier mobility, though. — user57037, Feb 19 '17 at 07:09
Sigh! You've searched for other questions with 'conventional', 'current' or 'direction' in the title on this site, haven't you? — Neil_UK, Feb 19 '17 at 07:20
If you cut a wire and put it in a glass of salt water, the current (Na+) will flow from the more positive terminal of this resistor to the more negative. Why is this idea so erroneous? — Oskar Skog, Feb 19 '17 at 07:33
A hole is something abstract, and will probably make sense when you try to understand semiconductors. Conventional current was defined at a time when we thought the electrons were positively charged, oops we were wrong, so no conventional current still flows in the same direction as the positively charged particles, or absence of negatively charged, or opposite direction of negatively charged. — Oskar Skog, Feb 19 '17 at 07:36
I'm voting to close this question as off-topic because it isn't a question, it's a rant. — uint128_t, Feb 19 '17 at 16:56
Possible duplicate of [Was Benjamin Franklin wrong (about conventional current)?](http://electronics.stackexchange.com/questions/39847/was-benjamin-franklin-wrong-about-conventional-current) — The Photon, Feb 19 '17 at 17:10
@Talldude I consider my self advanced (or maybe semi advanced) and I was taught both conventions, I assume most other engineers are also. — Voltage Spike, Feb 21 '17 at 18:34
I’m voting to close this question because I agree with the person saying it's a rant, not a question. — Hearth, Aug 18 '22 at 01:09

Neil_UK · Answer 1 · 2017-02-19T14:58:42.763

When it was realised that current had a direction, it was also realised that in order to work with each other, communicate and learn, we needed a convention for which way was +ve and which -ve. Franklin flipped a coin, and voila, conventional current flows +ve to -ve.

Obligatory xkcd

I did wonder whether the convention was set having noticed which way metals moved during electrolysis, but looking at the timeline, it was set prior to electrolysis.

It doesn't matter what convention we use, like it doesn't matter which side of the road we drive on, as long as we all do the same thing.

When you fully realise it's a convention, you'll also see that it doesn't matter which way round the convention is.

If you want to design semiconductors from the physics up, you'll be using electrons and holes and valance bands and quantum mechanics, like a motor mechanic would use pistons and bearings. Pistons work whichever side of the road we drive on. Electrons work whichever way our ammeter is labelled.

score 3 · Answer 2 · answered Feb 19 '17 at 14:49

In addition to Neil's good answer (+1), electrons aren't the only things that move to make current. Charges come in both positive and negative varieties. Protons, for example, have a positive charge.

Current is charges flowing, not necessarily electrons. In a solution, current can be the physical movement of positive ions, for example. In that case things are moving in the same direction as the conceptual current.

Early on, someone arbitrarily picked which polarity of charges would be called positive and which negative. It turned out later than electrical conduction in copper wire happens because of motion of electrons, which were arbitrarily decided to be negative. So for the case of current in copper wire, conceptual current flows in the opposite direction of the tiny little thingies that actually move, but that is irrelevant.

When doing electrical engineering, don't get hung up on the underlying mechanisms. Everything works fine by using conceptual current. It doesn't matter that in some cases that current is realized by negative thingies physically moving in the opposite direction.

Current direction

2 Answers2