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Electrostatic discharge

  1. Feb 7, 2015 #1
    Dear all,
    I would like to ask you to explain me this question on physical (chemical) level.

    Question is:
    Why static electrical charge is moving when I press and move my hand on rug and then catch a piece of iron, which is not gorunded?

    According to my knowledge, iron atoms had not strong binding energy between core and electrons on valence layer and so iron should not catch any negative or possitive charge from my hand.

    MY explanation is, that when I press and move my hand on rub, my surface atoms on skin is losing negative charge and then when I catch a piece of iron my hand is catching electrons from iron.

    Please, reply your explanations and opinion.

    Last edited: Feb 7, 2015
  2. jcsd
  3. Feb 8, 2015 #2
    Is this question write opaquely? Or is it so easy or hard, when nobody reply on it?
  4. Feb 8, 2015 #3
    I'm not sure if I'm answering your question or not, but my understanding is that your skin will have an excess of electrons that will jump to the iron. Because metals tend to lose electrons readily, I would assume that the iron already has some positive 'holes' in it, and the electrons on your hand are able to jump and fill them. Someone please correct me if this is wrong.
  5. Feb 8, 2015 #4
    Thank you very much for reply, it is answering my question.

    I have just some arguments againts your arguments:

    Men skin according to triboelectric table is easier releasing electrons and rub is usually constist of some ryaon, which is attracting electrons in more times. So I think, that men skin is possitive charged after conneciton with rub.

    Metal (is not so good conductor as copper) is somewhere in middle of triboelectric table (but it is more attracting electrons as releasing) so according to this and according to law that when two objects have different electrical potential between them, this potential is compenasted to be 0 -> I think that my skin should accept some electrons from metal.

    Is it possible?
  6. Feb 9, 2015 #5
    Is here someone who know the answer?
  7. Feb 9, 2015 #6
    The metal block, while not grounded, is still at a lower potential to your now charged up hand. The static charge equalizes these potentials (which is why it won't shock you twice in a row). Remember that voltage is relative to the two things being measured.
  8. Feb 9, 2015 #7
    Thnak you,
    I did not understand because I thought that my skin on hand is charged possitively, but when I am thinking about it now, it seems to be more probably that it is in reverse.
  9. Feb 9, 2015 #8
    I don't believe (someone correct if I'm wrong) the charge of your hand really matters, as long as sufficient potential exists between you and the conductive thing you're touching, you will receive a static shock.
  10. Feb 9, 2015 #9
    You need to have some no needed electrons on your skin according to me, because binding between electrons and protons in your skin is strong. So your skin need to be charge negativelly, but atoms of metal have orbitals lower energy levels so this electrons on your skin skip to metal according to me.
  11. Feb 9, 2015 #10
    What I meant by the charge (+ or -) not having significance is that, from your frame of reference getting shocked, the direction of electron transfer is imperceptible. That is, whether the electron transfer is from you to the metal (in the case of a positive charge) or the metal to you (negative), you still feel that pop the same.
  12. Feb 9, 2015 #11


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    Staff: Mentor

    That is not correct. A static discharge from your hand to a metal object can occur regardless of whether your hand is positively charged or negatively charged. It can even be neutral if the metal object itself is highly charged. The atomic and molecular orbitals are insignificant here since you have several thousand volts between your hand and the metal. They simply don't matter.
  13. Feb 9, 2015 #12
    It is true, because there is big potential difference between these two object, when your hand is charged.

    Thank you all very much, during this discussion I discover many new things which I did no know and also clarify some my statements.

    I want to have organised my knowledges better and better so I will study more and more.
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