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Electrons in a wire

  1. Aug 7, 2010 #1
    hey,
    I've been reading about how currents flow through a wire. I've read that a socket just produces an electric field, it doesn't produce electrons.
    My question is if a socket or lets take the case of a battery, if I connect a battery with a wire, say shorting it. The electrons in the wire flow because of the electric field, so why doesn't it run out of electron? I mean there's gotta be finite number of electrons in a wire.

    also, I don't understand how shorting works, why does the current stop, is it because the 5V of push by the battery eventually dies?

    I'm a little confused a help would be nice.
    Thanks
     
  2. jcsd
  3. Aug 7, 2010 #2
    Because batteries aren't ideal voltage sources. When you model a battery you include a resistor called internal resistance, so basically when you short it all the voltage drops across that resistor.

    The battery doesn't "run out" of electrons because every electron coming out will require an electron to go in to the negative terminal. That's why when you make a battery electrochemically you need some sort of salt bridge or a porous disk to allow balance of charge.
     
  4. Aug 7, 2010 #3
    Continuously supplied by the battery.

    Yes.
     
  5. Aug 7, 2010 #4
    5V doesn't "die", we model "dyiing" batteries as increasing in internal resistance, so by the time you suck all the juice from your battery the IR will be like 4 Meg-ohms so even if you short the battery there will be approx no current in the wire.
     
  6. Aug 7, 2010 #5
    thanks guys I got it. :)
     
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