charges on conductors

Discussion in 'General Electronics Chat' started by naveenbabu, Dec 28, 2012.

  1. naveenbabu

    Thread Starter New Member

    Dec 28, 2012
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    can some one say me how does excess charge on a conductor resides only on its surface

    please,,,,,,,,,
     
  2. MKCheruvu

    Member

    Nov 20, 2012
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    Electrons in a material are available in Atoms placed in lattice covalent bonding ie thru out the material. However in a conductor the electrons are loosly bonded to the atoms' Nucleus and can be dislodged with small electric potential .This dislodged electrons flow(displacement) contributes to the current. Depending upon weather the potential is unidirectional(DC) or Bidirectional(AC) the current flow direction changes .

    If the current is unidirectional the current flows across the total cross sectional area of the conductor. The bidirectional current flow leads to self induction(Lenz's law) property(inductance) and at high rate of change of current(high frequency) the current starts flowing on the surface only. This phenomenon is known as Skin Effect .Due to this the cross sectional area of conduction of conductor reducess and there by the Resistance(Impedance) of the conductor increases.
     
    Last edited: Dec 28, 2012
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  3. russ_hensel

    Well-Known Member

    Jan 11, 2009
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    Excess charge moves to the surface because the charges repel each other and are trying to get as far apart as possible. It is that simple.
     
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  4. Ron H

    AAC Fanatic!

    Apr 14, 2005
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    I'm pretty sure the OP was not asking about skin effect.

    I like Russ' explanation.
    Here is another one.
     
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  5. WBahn

    Moderator

    Mar 31, 2012
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    A slight variant on the explanation given in Ron H's link, imagine that an excess charge were placed somewhere in a conductor. This would result in a net electric field and the other charges, which are essentially free to move in all three dimensions, will move as a result. They will continue to move as long as there is a net electric field inside the conductor. But once a charge (any charge, not necessarily one that was placed in the interior) makes it to the surface, it is no longer free to move in any direction, but instead only along the surface (or back into the interior). So the surface charges will move until the electric field at the surface has no component tangential to the surface (otherwise they would keep moving). The end result is that charges migrate to/from the surface in such a way as to kill the entire net field within the conductor and everything except the normal component of the field (external to the conductor) at the surface.
     
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  6. naveenbabu

    Thread Starter New Member

    Dec 28, 2012
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    tnx sir for ur kind effort tht u have put in .this may be simple but i was breaking my head for this one for many days bcos i dont hve proper guidance for my studies .tnx u sir once again..... :):)
     
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