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Voltage in a battery

  1. Feb 19, 2015 #1
    Hi :)
    It might seems a stupid question but I can't find any answer for it ^^

    I have a question: how voltage is calculated in a battery?

    Let's say you create a battery with - 1 C of charge of electrons on the and the other side + 1 C of charge, could you tell me what is the voltage of this battery? According to Coulombs law the force F needed is (kQ1Q2)/distanceĀ² If we keep this track the potential energy W = F X distance which will give us kQ1Q2/distance, so voltage is still distance dependent, right? Is it calculated from a mean distance between the two terminals (like the middle of each cell?)

    Thanks for your help!
  2. jcsd
  3. Feb 19, 2015 #2


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    That is an effect of the potential of the metals and chemicals used. Take a piece of steel and a piece of aluminum, connect wires to them and lower them into the sea (not the freshwater kind) a couple of centimeters apart. You have now created a battery, it is able to drive a current through an amperemeter.
  4. Feb 19, 2015 #3


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    Thats not how a battery works. Batteries don't seperate charges like a capacitor does. They use chemical reactions to create a voltage. Each electrochemical cell's voltage depends entirely on what its made of. There are charts and tables all over the net that can tell you the voltage for a particular type of cell.
  5. Feb 19, 2015 #4


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    Don't feel stupid....
    http://en.wikipedia.org/wiki/Battery_(electricity [Broken])

    Last edited by a moderator: May 7, 2017
  6. Feb 19, 2015 #5
    Thank you so much! I know now where I need to look at :)
  7. Feb 19, 2015 #6


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    Not right, as a general principle. Voltage is PotentiaL Difference, which does not depend on distance apart of battery plates or length of wire. It depends upon the Energy that's been given to Charges (Volts = Joules per Coulomb).
    It is true that, for a particular Field (=Volts per Metre) then the PD across two points in that field will be dependent on their separation. But that is not relevant to batteries - unless increasing distance involves inserting more battery cells in series.
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