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B Electrostatic Potential: Value at zero distance from charge

  1. Jun 21, 2016 #1
    Formula for Electrostatic Potential due to a point charge is V=1/4π∈ Q1 Q2/r

    This implies that at r=0 value of the potential should be infinity.

    Is it True.

    If that is the case then how we say the terminals of a battery having positive and negative charge are having definite value of potentials. I think as per the formula potential of terminals of battery should also be infinity?

    Some one please clarify
     
  2. jcsd
  3. Jun 21, 2016 #2

    mathman

    User Avatar
    Science Advisor
    Gold Member

    Battery terminals are not points. When you get close enough to a "point" charge, classical theory breaks down and you need quantum theory.
     
  4. Jun 21, 2016 #3
    I understand Battery terminals are not points. But they create a driving force for electrons to move in an Electric Circuit.

    cellabel.gif



    If you see the above figure copied from "http://hyperphysics.phy-astr.gsu.edu/hbase/chemical/electrochem.html". I dont understand how potential is created in the battery terminals?

    Potential is created by charges. Here we have Zn Charge and Cu Charge, How potential develops in the electrodes?
     
  5. Jun 21, 2016 #4

    Dale

    Staff: Mentor

    In physics you cannot just blindly go plugging numbers into formulas. You need to know the limitations or approximations or assumptions of a formula.

    Coulomb's law is limited to the outside of a spherically symmetric charge distribution. The terminals of a battery are not spherically symmetric, and even if they were their radius would be finite.
     
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