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Negative ions, static charge

  1. Apr 22, 2014 #1
    In a famous experiment with a balloon and wool.


    Initially the balloon and wool pullover have no ions.

    I understand how positive ions are formed, that you apply energy to the electron, thus electron overcomes the attracted force created by a proton, but how are the negative ions created?

    I assume when we rub the balloon with a wool pullover we apply energy to both materials, thus depending on a material (how tight electrons to the nucleus) electrons are escaped from both materials forming positive ions.

    BUT, I dont understand how the negative ions created, why would atom which is in equilibrium get more electrons and why at the end we get 2 charged materials?
  2. jcsd
  3. Apr 22, 2014 #2


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    Science Advisor
    Gold Member

    For positive ions, an electron or more is stripped off.

    So to make negative ions, one or more electrons are added.

    These electrons need not be associated with a particular atom; for polar materials there is a weak dipole field available to do the pulling/repelling. For a conductor the extra charges just "float about" or are taken from the "electron sea" of conduction electrons.

    Rubber balloons and wool sweaters were chosen for a reason: they have the properties required to hang onto or loose electrons.

    There is a good presentation at: http://www.regentsprep.org/Regents/physics/phys03/atribo/default.htm
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