Electron Flow

Discussion in 'Feedback and Suggestions' started by seecumulus, Jul 18, 2011.

  1. seecumulus

    Thread Starter Member

    Jul 13, 2011
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    I just completed reading your Transistor Theory ( first page Introduction ).

    I like that the Author of this e book at this point is using Electron Flow
    vs Conventional Flow.
    I learned initially that Current flows the way the Electrons Flow and
    of course this is the way I like all my Electronic's material to read.
    :)
     
  2. MrChips

    Moderator

    Oct 2, 2009
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    Here we go again.

    Someone in history tried to be politically (and scientifically) correct by attempting to change all of electricity and electronics text books.

    For most of practical electronics, it does not matter whether you use electron flow or conventional current flow. It is all relative.

    It is as if the Aussies wanted to argue that they are on top of the earth and the rest of us are below them.

    Sorry, I use and teach electronics using conventional current flow. Current flows from higher potential to lower potential.
     
  3. steveb

    Senior Member

    Jul 3, 2008
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    I've never really understood the dislike some people have for conventional current flow. It makes perfect sense in terms of vector math and incorporation with all other physics equations. You just think of charge direction (shown by an arrow in a circuit or defined by a coordinate system in a EM field problem) times charge as the sign of the current flow. Negative charges going against an arrow is mathematically equivalent to positive charges going with the arrow. If you have a physical problem where you know the charges are electrons, then you know they physically move in the opposite direction to the current flow direction. It's just a definition and a convention and is only confusing if you don't invest a little time to work out the implications in your head.

    Sure you can use electron flow, but it is no more intuitive than conventional flow. It seems better when you first start learning, and seems worse when you become advanced and try to deal with the rest of physics. The real problem is that the electron was defined (unknowingly by good old Ben Franklin) to have a negative charge. Had he known about electrons, they would have been defined as positive charges, and then all physics equations (that historically followed) would have considered and incorporated that convention and everyone would be happy. But, it didn't happen that way and we have to live with whatever confusion it causes us at first.
     
  4. Wendy

    Moderator

    Mar 24, 2008
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    Good luck using tubes, CRTs, E Beam welders, sputtering machines, and many more devices. Maybe in your world it doesn't matter, but in the larger scheme, it matters. Not to mention just plain physics.

    When I learned electricity at age 6 I understood the basic concepts. They aren't difficult, and are fundamental to understanding the atom.
     
  5. MrChips

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    Oct 2, 2009
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    My world happens to be the Department of Physics & Astronomy at a major university. This is the way we teach electronics.
     
    Last edited: Jul 18, 2011
  6. Wendy

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    Mar 24, 2008
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    Doesn't make it right, just means a lot of students may have relearn what you teach, if you are teaching conventional flow. Just because it was good enough for Ben Franklin doesn't mean it should still be taught that way, he selected it because he didn't have the tools to tell the difference. We do.

    As I mentioned is post #4, there are quite a few electronic devices that direction of flow matters, it deals directly with theory how they work. So if you have to teach one standard, why teach a second (other than to acknowledge it used to be the standard). We have had students wander into this site thinking conventional flow was the correct and only explanation. Their teachers had done them no favors.

    Truthfully, I don't think about it one way or another when I design, I just use what I know.
     
    Last edited: Jul 18, 2011
  7. PatM

    Active Member

    Dec 31, 2010
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    When I was teaching a General License Class back in 1978 one of the other instructors (who was a Engineer) was teaching the Advanced Class.
    I thought he was going to have a heart attack when he discovered that I was teaching Electron flow. (Which I was taught while in the US Army radio repair class.)
    As far as I am concerned it doesn't make much difference which you learn, as long as you don't mix them up.
    As mentioned, back in the tube circuits days, electron flow made more sense to me.
     
  8. steveb

    Senior Member

    Jul 3, 2008
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    Bill, your explanations on this subject are very open to misinterpretation and actually seem to misrepresent the facts.

    You say, "doesn't make it right, as if it's wrong", when in fact it's just a convention which, by definition, isn't right or wrong, but just an accepted way of doing things.

    You say, students "may have to relearn what you teach" which is also wrong, although it is good to know both standards, whichever you learn first. All one needs is common sense understanding of what the definitions mean physically and there is no difficulty to either method.

    You mention Ben Franklin's lack of tools as if we can correct his unlucky choice with the electron flow definition, when really we can only correct it by defining electrons to have positive charge and then changing any relevant physics equations accordingly. Well, we're not going to rewrite the few centuries of text books, so forget that.

    Let's face it, if someone can't figure out what direction electrons move in a tube, CRT or wire etc., just because of the definition of conventional current, they are not going to go far in this field. The conventional current definition explicitly specifies that electrons flowing against the arrow is positive current in the direction of the arrow. No confusion there at all, unless you just don't get it. This idea that conventional current is non-physical or non-intuitive is totally incorrect, although the beginner may struggle a little more at first. However, after a short while, it doesn't matter, and actually, any student that is in it for the long haul will be better served by getting used to conventional current right away. This is simply because all intermediate to advanced physics and engineering texts and institutions use the conventional current flow definition. Why is that? To be compatible with mechanics. In mechanics we like velocity to also have a direction and sign. If current is I=qv, where q is charge and v is velocity, then the conventional current definition begins to make more sense. I=-ev for the electron, where e is the charge of a proton. So, what happens if velocity is negative? Then the current is positive. So the sign of both the charge and the velocity play into the sign of the current. So, there is some logic here, but note that it is not logic in the sense that it is absolutely right, but just convenient enough to make it the more accepted standard when mechanics and field theory merge together.
     
    Last edited: Jul 19, 2011
  9. Wendy

    Moderator

    Mar 24, 2008
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    OK, but the fact is the sticky is up because we did have a flurry of students who were willing to argue what you so blithely accept. Blame them, blame their teachers, but it doesn't change that one simple fact. I don't believe I've misstated anything, and like as not, it is the convention in this book because it agrees with the standard model of physics, where as conventional current flow doesn't. It really is that simple.

    People have to know conventional current flow because it is so entrenched. It was the standard for around 150 years, and a lot of text books were written in that time. As a Mason I understand how hard it is to change tradition, but this is a mite ridiculous.

    And I did understand the difference at a young age. I've always been a science buff. I may not be as sharp as a lot of the guys on this site, but the facts really are pretty clear cut on this issue. When I learned devices (which was self taught), I always thought of the arrows pointing to the source of electrons. It is all in how you think of it.
     
  10. steveb

    Senior Member

    Jul 3, 2008
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    You have misstated a few things, as I mentioned above. Here you are misstating again. The author devotes a full page to explaining the two conventions and why he ultimately ("begrudgingly") chose the electron flow convention. Nowhere does he say he used it because it agrees with the standard model of physics. If that statement is made anywhere else in the books or in a "sticky" then it should be corrected, since it is misinformation.

    In fact, neither convention agrees or disagrees with the standard model of physics. They are conventions, - nothing more and nothing less. Conventional current defines the flow of charge in a mathematically consistent way and makes no reference to wires, tubes or electrons. The fact that electrons happen to be the primary charge carrier in many devices we use in electronics has nothing to do with how we set up a convention to do calculations. They are independent things, and there is no basis to say it disagrees with the standard model. There is also no basis to say that it makes working with tubes and wires so difficult that one needs "good luck" to do it.
     
  11. Wendy

    Moderator

    Mar 24, 2008
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    Except the second post protested the use of this convention in the book. You may disagree with the AAC book as I disagree with your point of view. This is not a direct argument about about the conventions, I have stated the convention theory needs taught as a relic, but about what standards should be used, especially concerning the text book this site was designed around.

    I notice you have sidestepped the point of people not understanding conventional vs electron flow. Which one would you pick as the first to teach? Would you let a statement stand that conventional is correct, and electron flow is wrong?

    Uh, no, this is false.

    The charge carrier is electrons. There is no positive charge carrier movement in wires. In medium outside wires this can change, but we use wires, so we'll have to agree to disagree on this point. I prefer physics and reality over mathematical models. Conventional current flow is a convention, electron flow is the reality, and trying to say it any other way is plain false and disingenuous. If the coin flip from Ben Franklin had gone the other way we wouldn't having this conversation. I understand why the convention is used, just like I understand why AM is taught the way it is. You start simple, then work your way into the way it really works (IE, sidebands).
     
    Last edited: Jul 19, 2011
  12. steveb

    Senior Member

    Jul 3, 2008
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    I don't disagree with the AAC book at all, but I do disagree with a few of your statements, particularly the ones I pointed out.

    No. As I said, they are both conventions and hence are both neither right nor wrong. They are different methods of doing the same thing. Just be consistent, and you will be ok.

    Personally, I don't think it matters which convention you learn first. If you can't understand the point of having conventions and can't disconnect the method from the physical understanding, then another career path choice is in order. I think both conventions should be introduced conceptually and then one needs to be used for a long time consistently while the student masters the craft of analysis. Switching later will not be very difficult, if needed.
     
  13. Wendy

    Moderator

    Mar 24, 2008
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    The basic point of disagreement boils down to I do not think the electron flow theory as a convention. It describes the reality, accurately, and yield predictions and predictable results that conventional flow can't, the very definition of science. Many physical processes depend on it. This is why it was selected for the AAC book, which does acknowledge conventional current flow theory and then chooses not to use it. Tis OK though, you are not going to convince me and I'm not going to convince you.

    There is a reason the sticky was locked.
     
  14. MrChips

    Moderator

    Oct 2, 2009
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    Never once did I protest the use of electron flow on AAC or any place else. All I have said is conventional current is the way I have learned it and continue to teach it to university students. This is a dead argument and I refuse to argue on either behalf.
     
  15. steveb

    Senior Member

    Jul 3, 2008
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    OK, it's not a convention when you talk about what direction electrons are actually moving in a particular situation. However, if you want to use the electron flow concept as a tool in analysis, it automatically becomes a convention in practical use. Otherwise you would need to be able to predict the direction of real electron flow in EVERY component and make EVERY arrow definition correctly beforehand. In complicated circuit analysis problems, you can't do that reliably. Hence, some of your currents come out negative, meaning that you put the arrow in the wrong direction when you set up the problem. This is the classic issue of setting up reference frames and it is an issue of convention. So, the rest of the world considers it a convention, even if you don't.

    On the other side of the issue, when it comes to describing a simple device, like a tube, the conventional current description is just as cabable of describing reality accurately and make predictions. We do this type of thing all the time in the real world. You just making a statement that "conventional flow can't do this" is indefensible and holds no water at all. With conventional current definition, the arrow shows the direction of negative velocity for the electrons. Pointing the direction of negative velocity may seem unusual to a beginner, but it has clear meaning and is really no more unusual that saying that electrons have negative charge, which is the crux of the whole matter.

    If we accept your thinking, we would have to conclude that physicists would be unable to describe the current due to a proton beam using the electron current convention. But, of couse that would be a ridiculous statement too.
     
    Last edited: Jul 19, 2011
  16. someonesdad

    Senior Member

    Jul 7, 2009
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    Wow, a real tempest in a teapot. :p I've gotta go floss my cat.
     
  17. Wendy

    Moderator

    Mar 24, 2008
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    This will be the third (and final) time I'll say this. We don't and won't agree with each others point of view. There is no misunderstanding between us, and I've stated my case clearly as I can.

    I'm done with no hard feelings in any way. :D Neither of us is Ratch.
     
  18. steveb

    Senior Member

    Jul 3, 2008
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    Yes, and if you try to insist the storm in there is spinning clockwise, I'll remind you that you only think so because you are looking down from the top, and it's not wrong to say it's counterclockwise, if you define the convention accordingly.
     
  19. someonesdad

    Senior Member

    Jul 7, 2009
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    You just need to say, "No, your other clockwise". :p
     
  20. #12

    Expert

    Nov 30, 2010
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    Conventional flow has its uses. Just consider that the picture on the crt is produced by opening the flow of current to the cathodes at just the right time and in just the right amount for the light to turn into electricity and jump into the power supply so it can be drained into the wall outlet. It is this kind of magic that keeps us employed.
     
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