Electron Flow Notation, clarification

Discussion in 'General Electronics Chat' started by kclv1988, Dec 11, 2015.

  1. kclv1988

    Thread Starter New Member

    Apr 17, 2007
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    I just wanted to get a clarification on the "Electron Flow Notation"

    1. EFN, explains what is actually happening? (Yes)
    2. Negative side of a battery is called negative because it has an surplus of electrons? therefor negative in charge.
    3. Positive side of the battery is called positive because it has a deficit number of electrons, and therefor has a positive charge.
    4. Electrons which are negatively charged flow from the negative side to a positive side.
     
  2. JohnCase

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    Aug 19, 2015
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    It's right from what I know (I'm a student). You only have to pay attenction couse the CONVENTIONAL notation was created on the very beginning of electronics science and saids: the current flows from positive to negative.

    We still use this notation on the circuits, but the real things are different. It worked and works, but it's usefull to know!

    Cheers.
     
  3. alfacliff

    Well-Known Member

    Dec 13, 2013
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    currwect flows from negative to poitive. there was a 50-50 chance when someone dicided which way electrons flow. electrons have a negative charge, thus are attracted by a posi9tive charge. getting electrons to flow out of a positive source takes a more positive charge.
     
  4. MikeML

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    Oct 2, 2009
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    No, let's get it right.
    Electrons move from negative to positive. Current (which is defined as the movement of positive charge) flows from positive to negative.
     
    Last edited: Dec 11, 2015
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  5. ErnieM

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    Apr 24, 2011
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    Do yourself a favor and forget about why how who said electrons go what way for current to flow.

    The scientific answer, the engineering answer, and the industry standard answer all agree that current is defined as a flow of positive charge from positive to negative.

    Electron flow is an unscientific concept put forth by people who think they know better. They may have other bad habits as well.
     
  6. nsaspook

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    Aug 27, 2009
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    Maybe a little too harsh as Electron current is a subset of conventional current. As a purely electrical parameter the selected conventional current flow direction was arbitrarily defined. Abstract current is a property (rate quantity) not a thing or entity. When you need to work with electrical properties or parameters use conventional current. When you need to understand physical movement of the charge entity then a non-arbitrarily defined flow current might be important to understand the properties of a system that are not purely electrical like batteries that can have simultaneously flowing currents with positive and/or negative ions in opposite directions.
     
    Last edited: Dec 11, 2015
  7. crutschow

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    Mar 14, 2008
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    Where did you ever get that idea? :confused:
    I defy you to give a reasonable theory of the operation of vacuum tubes (valves) without invoking electron flow.
    (I do have some other bad habits though). :rolleyes:
     
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  8. MikeML

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    Certainly, you can talk all day about which way electrons swim in a vacuum. Just don't call it Current (with a capital C)!

    The current in my huge Kilowatt RF amplifier flows from the plus side of my 3000Vdc power-supply, through the plate choke into the plate of the 3-500Z tube, out the cathode, through the plate current meter and back into the negative side of the 3500Vdc supply... Who cares what happens inside the glass?

    If you don't believe it, which way around do you suppose the plate current meter is wired in the circuit. Is the + end of the meter tied to the cathode or to the negative side of the supply?
     
    Last edited: Dec 11, 2015
  9. crutschow

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    Of course the Current (with a capital C) flows from plate to cathode. I certainly wasn't suggesting otherwise, but you missed my point.
    Perhaps you don't care what happens inside a vacuum tube but some (including myself) are curious about how they work. And unless you want to say that the theoretical positive charges are mysteriously pulled from the plate to land on the cathode, you need to use negatively charged electrons to explain how the charges are boiled off the hot cathode to travel to the positively charged plate (and how the grid with a negative charge with respect to the cathode controls this charge flow).
    Personally I always use Current when doing circuit design and find it difficult to use electron flow for such analysis. But the description of some things, such as the inner workings of vacuum tubes and semiconductor electronics require the use of electrons as charge carriers.
     
  10. MikeML

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    Certainly, we agree on that.

    btw-I played with tubes long before I started on semi-conductors, so can relate... I still have both a RCA Radiotron Manual and a GE Tube manual around here. As we speak, I am restoring a tube-based Heathkit SB610 Modulation Scope...
     
  11. hp1729

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    Nov 23, 2015
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    Good, but this story falls apart when we get to chemistry and solid state devices. We have to keep in mind that for every electron that goes from negative to positive there must also be a hole it fills and leaves behind, meaning there was a positive charge going positive to negative. We can't have one without the other.
     
  12. kclv1988

    Thread Starter New Member

    Apr 17, 2007
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    Wait what hole? Doesn't the negative side of the battery contains a surplus of electrons? So when one electron leaves, it doesn't leave any holes behind.

    Btw I simply summarized the info found in chapter 1, Just want to make sure I understood correctly.
     
  13. WBahn

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    Mar 31, 2012
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    People that engage in electron flow almost always do so incorrectly because they want to define a positive current as the flow of so many electrons in the direction that the electrons are physically moving. Fine so far. But then they want to continue using the same voltages as the rest of the world and want to use the same equations as the rest of the world and thereby set themselves up for using a system that is so intrinsically self-inconsistent that they have to learn when and where to apply magical mystery minus signs to make everything work out.

    Current is the flow of charge. The flow of positive charge from A to B is the same as the flow of negative charge from B to A. There are almost no instances in which the distinction is relevant, and that includes vacuum tubes. There are plenty of instances in which how charge carriers move is important, but that is separate from the question of how charge moves. About the only cases where it makes a fundamental difference are those involving the Hall effect or similar instances involving transverse voltage potentials related to the interactions between currents and magnetic fields.

    Now, I sense that you have a too-simplistic notion of a battery in that you are thinking that it has a bunch of electrons on one side and a deficit on the other. In reality, the actual surplus is effectively negligible. The following blog post might help:

    http://forum.allaboutcircuits.com/blog/a-battery-isnt-a-capacitor.588/
     
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  14. hp1729

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    Nov 23, 2015
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    Of course it leaves a hole :)
    In a normal there is an equal number of electrons and protons. When an electron is pulled away that atom now has a positive charge, a "hole". Diodes and transistors are hard to explain if you just talk about electrons.
     
  15. #12

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    Nov 30, 2010
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    And therefore, a correct way exists.

    Personally, I can think in either method. The trick is to be consistent within the circuit you are working with. Vacuum tubes are easier to think of in electron flow. If you don't, you have to use a model where the charge magically knows which part of the CRT screen to jump off of in order to display the picture correctly and all those equations about velocity, charge, the mass of an electron, and (electrostatic or electromagnetic) deflection look like nonsense. Transistors are usually easier to think of in conventional flow. With the top of the drawing labeled as a positive voltage, most of those clumsy negative signs disappear when you think in conventional flow. It's all the same to me, but it wasn't in 1960 when transistors were pretty rare critters. I had to adjust to conventional flow just as much as today's students have to adjust to electron flow when it is the right tool at the moment. Notice the word, "tool". Whether you think in conventional flow or electron flow depends on what is the right tool at the moment.

    I still revert to electron flow when I get confused, but that is caused by my personal weaknesses caused by learning electronics when vacuum tubes were almost the only thing we had to work with. The agreement on this website is that we use conventional flow, and I can almost always comply with that rule. When we get a question about a cathode ray tube, I have to hope the other local denizens will indulge me on that particular problem.
     
  16. KL7AJ

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    Nov 4, 2008
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    Well, you can blame Ben Franklin for all the chaos and confusion. :)

    Actually, if you look at the history, it made perfect sense. Uncle Ben described the flow of current in ELECTROLYTIC solutions, long before anyone knew about the electron. What he observed (such as during the electroplating process) was the flow of IONs, not electrons. So, actually ION flow is "actually happening" too!

    Fortunately the numbers all work out the same anyway, so you can pick any model you like....the only one who might get mad is your professor. :)
     
  17. ErnieM

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    Unfortunately while the numbers work out correctly for most tasks the sign is dead wrong that can mess things up, such as now having to use some sort of "left hand rule" when seeking the direction of an induced magnetic field.

    The SI (International System of Units) defines current as the flow of positive charge across a surface. A flow of negative charge the other way involves the product of two negative signs, so "electron" current still has the same positive sign.

    Define the current as going the wrong way and you make an error at step one.
     
  18. #12

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    Last night, I found out my nephew is going to buy me a flat TV for Christmas. In about 5 or 6 weeks I can stop making these chronic mistakes about electron flow.:)
     
  19. WBahn

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    Oh yes, a correct way to do it definitely exists. A couple of them, in fact.

    The simplest and purist is to recognize that as soon as you say that a current of 1 ampere is flowing from terminal A (what we call the negative terminal) of the battery to terminal B (what we call the positive terminal), that you have just declared the electron to be positively charged (since you are saying that one coulomb of charge is being transferred from terminal A to terminal B each second). If you then want to continue using the same equations that everyone else uses, as opposed to throwing all kinds of minus signs into most of them, then you have to redesignate terminal A as being positive relative to terminal B. The end result is that everything stays consistent as long as you multiply every voltage by negative one as part of saying that you are going to use electron flow.

    The other way is to go through all of the equations related to electricity and magnetism and determine which ones needs to have minus signs either added to them or taken away from them. Most do, but some do not.

    But practitioners of electron flow do neither. Instead, the ignore what the equations require and then adjust the results for what they know (or think they know) should be the answer, applying magical mystery minus signs as needed. But that is very limiting because you have to break the process into a bunch of steps that allow you to apply the magic in small enough chucks that you can think about it clearly. Whereas if you use a consistent model then you can propagate the work through the entire system, no matter how complex, and know that the sign of the final result means exactly what it says it means.

    As for thinking in electrons for vacuum tube work, I agree. But that isn't a matter of conventional current or electron current. That is merely a matter of working with the flow of charge carriers instead of charge.

    The website is actually psychitzophrenic on this point. The E-book (and, by association, the website) officially uses electron flow (and usually uses it wrong) while the unofficial consensus of the forum members is to use conventional flow. And this dichotomy does create problems from time to time. But we are able to muddle through with it. Even if the E-book and website were thoroughly committed to conventional flow (and talking about charge carrier motion when appropriate is completely consistent with this), there would still be problems because of all of the people come here for held that were taught using electron current flow model (and taught it incorrectly).
     
  20. BR-549

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    Sep 22, 2013
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    I can understand denoting a reverse flow of negative charge, as a positive flow. In that context.

    But one volt will not cause one coulomb of positive charge flow across one ohm.

    They need to change that standard to negative charge.

    Ohm's and the other laws only apply to negative charge.

    We do not flow positive charge. If we did, we would need new proportional equations.

    Positive charge weights 2000 times that of negative charge.

    If we did use positive charge............there would be a noticeable inertia and weight gain of circuit, with increase in current.
     
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