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Electron debt

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  1. Apr 15, 2008 #1
    scenario:

    If any generator ultimately 'pushes' current (free surface electrons) down a wire, moving trillions of trillions of electrons through power wires towards our homes and other uses . . .

    what is the source of electrons at the generator site to replenish electrons? There can not be an endless supply, so where are they initially taken from, and how are electrons returned to this starting point of electrical generation (in this specific example or in general for non-cyclic systems).
     
  2. jcsd
  3. Apr 15, 2008 #2

    Mentz114

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    The electrical circuits are closed loops. The electrons just go all the way round and start the journey again. Thats for DC. If it's AC, they oscillate, moving one way then back again repeatedly.
     
  4. Apr 15, 2008 #3
    fair enough for a conventional circuit, but i was asking about a situation where current is sent one way only, down a line to a "sink" for the electrons (appliances and whatever).

    I think i have found the answer that there is a component of the system in the ground. It is the ground itself that supplies (effectively) an endless supply of electrons for the generator (ie hydroelectric power plant). (Similar to a well drawing from an underground lake that is immediately, and constantly refilled as water is pumped out)

    If this needs correction or some specific detail on how the electrons are drawn out of the ground, I would appreciate it, but I am otherwise satisfied with the general explanation.
     
  5. Apr 15, 2008 #4

    Mentz114

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    The current is never sent 'one way', that's why there are two wires. There's no such thing as a sink for electrons. If your appliance is running, it is part of a closed circuit and the same electrons flow around the circuit. They are not in any sense 'used up'.

    Where did you find this ? I think you've got it wrong.
     
    Last edited: Apr 15, 2008
  6. Apr 15, 2008 #5

    russ_watters

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    If you have more than a tiny amount of current in your ground wire, you have a serious problem. The ground is there for protection only, not for carrying load. Note that most household electrical devices are not grounded - they only have two-prong plugs.
     
  7. Apr 16, 2008 #6
    but then, what energy that was used to turned on all these appliances? where did it come from?
     
  8. Apr 16, 2008 #7

    russ_watters

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    Again, the best way to think about it is probably with an analogy to a hydroelectric plant. The water goes through the plant, but is not consumed in the process. When it gets out at the bottom of the dam, it is just at a lower [gravitational] potential than before it went through the dam/plant. An electron going through a resistor works the same way. A force (also called "potential") is required to push the electron through a resistor (that's where the name "resistor" comes from) and after going through the resistor, the electron has a lower electrical potential than it did before it went through.
     
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