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I found this related question: What happens to 5 electrons on a sphere?

But this question describes the case when there can only be 5 electrons on that sphere at all times. The answer linked to the Thomson Problem, which gives a solution for the stable configuration of $N$ charges placed on a sphere.

  • So my question is that, will it not repel the extra electrons inside the metal to produce a state of non-uniformly distributed + and - charges?

If not, it would mean that there is a net non-zero field inside the bulk of the sphere, so that configuration cannot be a steady state, i.e. It will cause the sea of electrons to flow and achieve another steady state, which can be said from the Electrostatic Shielding Effect.

  • So, what steady state will be achieved?

  • What if it is a solid sphere and not a hollow one? Will the extra electron still be on the surface of the sphere?

Any help is appreciated!

P.S. You can leave the last question for me to attempt, if its easily deducible from the answer for the first two!

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My guess would be that it remains where you add the electron, assuming it's an isolated system. As for your question "Is it necessary to continuously have N and only N electrons on the sphere at all times?", can you please clarify that? –  mehfoos Jul 23 '13 at 10:35
    
@user1218748, changed the wording, hope it is clear now. –  udiboy Jul 23 '13 at 10:43
    
Sorry to be pedantic, but are you asking if the extra electron introduced will pull other electrons in the metal?? –  mehfoos Jul 23 '13 at 10:51
    
I'm sorry, A typo... –  udiboy Jul 23 '13 at 10:52
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1 Answer

up vote 3 down vote accepted

When considering a big enough chunk of matter, as in your experiment, you are dealing with it's macroscopic observed effects, where granular effects of single electrons are smoothed out . So if you add $n$ electrons to the electron sea of the metal the observed effect will be a uniform increase of $-ne\over S$ in the surface charge density of the metal.

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This implies I can distribute a single electron charge uniformly over a finite volume. How is that even possible? –  udiboy Jul 23 '13 at 11:57
    
@udiboy No, the observed effect is so. If you add thousands of electrons doesn't make any difference, all you observe is a smoothed uniform charge density. Because the electrons are moving and the charge density is constant. –  Mostafa Jul 23 '13 at 12:13
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Except that the excessive charges don't distribute uniformly in the volume, they would rather stay on the surface. –  Ali Jul 23 '13 at 12:31
    
@Ali Ah, I wanted to say the surface (not volume). But my point is still the same. Thanks. –  Mostafa Jul 23 '13 at 12:34
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