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I Charge accumulation for in series batteries

  1. Apr 13, 2017 #1
    Take the following diagram of 4 1.5V batteries connected in series to creat and net voltage of 6V (the numbers are of no significance here).
    batteries-in-series.PNG

    If we were to short circuit the system by connecting battery 1 to battery 4 (or run the current through a load), wouldn't there be electrons traveling from the positive terminal of battery 1 into the negative terminal of battery 4 and accumulating there? Wouldn't this then create a net positive charge in battery 1 and a net negative charge in battery 4 until the current is inversed? This would matter in a scenario where you allowed such a charge buildup to occur and then seperated the batteries leading to the permanent seperation of those charges, no?

    The way I see it, the electrons do not have a way of returning to the negative terminal of battery 1. This leads to my second questiong which is: why is there a net potential difference of 6V if the only 2 electrodes that are interacting are the positive of battery 1 and the negative of battery 4? Essentially I don't understand the interactions of batteries 2 and 3 and their effect on the net voltage. If someone could explain the path of an electron in this system I would be very appreciative.

    Thanks in advance!
     
  2. jcsd
  3. Apr 13, 2017 #2

    Dale

    Staff: Mentor

    No, there is no charge accumulation. For each battery, the amount of current entering one terminal is equal to the amount of current leaving the other terminal. So no charge accumulates.
     
  4. Apr 13, 2017 #3

    Drakkith

    User Avatar

    Staff: Mentor

    No, they would move from the negative terminal of battery 4 to the positive terminal of battery 1, not the other way around.
     
  5. Apr 13, 2017 #4
    Okay sorry, got electron and current flow inversed. So I think I see what you are saying, Dale. The electrons would flow from the negative terminal of 4 to the positive of 1. BUT, to compensate for this, the negative terminal of 1 will give and electron to the positive terminal of 2. And then from 2 to 3, and then finally the circuit is complete when 3 gives and electron back to 4. This would therefore result in electrons being put at a lower potential 4 times which accounts for the net voltage of 6V. Am I correct on this?

    In addition, if the circuit from 1 to 4 is NOT closed, why wouldn't electrons still flow from the negative terminal of 1 to the positive terminal of 2? Despite not being able to offer a regeneration of charge in battery 1, the electron would still be moving to a lower potential which should be favourable, no?
     
  6. Apr 14, 2017 #5

    davenn

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    Science Advisor
    Gold Member

    you have to ask yourself ... why would they move....
    1) when there is no charge imbalance in that setup ?
    2) when there is no complete circuit ?
     
  7. Apr 14, 2017 #6

    Dale

    Staff: Mentor

    Circuit theory has two governing laws: KVL and KCL. What you are describing would violate KCL.

    If you are learning circuit theory then you should never even use the word "electron", it is not even part of the theory. In circuit theory there are only voltages and currents and circuit elements. The voltages follow KVL and the currents follow KCL.

    That is not to say that it cannot happen, just that it is something that doesn't happen within the domain of validity of circuit theory. So you would need to use a more advanced theory like Maxwell's equations or quantum electrodynamics.
     
    Last edited: Apr 14, 2017
  8. Apr 14, 2017 #7
    Dale, that makes a lot of sense now. Current going out must equal to current going in so unless the circuit is closed nothing can happen. Thank you!
     
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