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Voltage difference = Infinity?

  1. Jan 4, 2012 #1
    Voltage difference = Infinity???

    So if there was a Q Coulomb point charge and a -Q Coulomb point charge with X meters of separation, and I wanted to find the voltage difference between those two charges...
    How would I do it?


    Since V = kq/r + kq/r in this case, wouldn't I have to divide by 0?

    V = Qk/X + -Qk/0

    Or to avoid the problem, I just made it REALLY close to the charge, like:

    V = Qk/X + -Qk/.0000001

    Then I'd get some obscenely large number for the voltage for BOTH sides... But I know I'm missing something pretty major here. The potential difference shouldn't be that huge.


    The reason I want to know is because I'd like to know how to calculate a battery's voltage by knowing just the charges without using capacitor equations.
    But I really can't figure this one thing out...
     
  2. jcsd
  3. Jan 4, 2012 #2

    Drakkith

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    Staff: Mentor

    Re: Voltage difference = Infinity???

    I'm not sure you are using the right equations. First, a battery isn't a capacitor, so why would you use the capacitor equations? The two are very different.

    Second, I really don't know the math, so if I'm mistaken I apologize, but googling V = kq/r + kq/r gives me stuff on charged spheres, not point charges. (Edit: Further googling says I'm probably wrong, so just ignore this if it's true)
     
  4. Jan 4, 2012 #3
    Re: Voltage difference = Infinity???

    Oh, I assumed a battery was like a capacitor in that it was just two terminals with opposite charges, like capacitor plates. Okay then, scrap that.


    But yeah, V = kq/r is applicable to point charges.
    I wanted to stay away from charged spheres for simplicity's sake.
     
  5. Jan 4, 2012 #4

    Drakkith

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    Staff: Mentor

    Re: Voltage difference = Infinity???

    Nope, a battery generates its voltage from chemical reactions. http://en.wikipedia.org/wiki/Electrochemical_cell
     
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