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David, Tutor
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Experience:  PhD in Theoretical Physics
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for david -- I understand that electrons disperse across the

Resolved Question:

for david -- I understand that electrons disperse across the surface of a conducting sphere to increase their distance from one another but why is the charge zero in the center, even in a solid conductor?
Submitted: 4 years ago.
Category: Homework
Expert:  David replied 4 years ago.

David :


First of all note that electrons are free to move inside the

conductor, so if there is even a tiny force acting on the electron it will move

basically it is not in a bounded state. Now you are correct that the electrons

accumulate on the surface because they tend to increase the distance between each other.

You are asking the question why the electrons cannot accumulate inside as well.

Look in principal if you think that there are many-many electrons all over the conductor

then they will accumulate inside as well because on the surface you have sooo

many electron that there is not even a spot for an extra one. Well this logic while seems reasonable is

an overkill, such situation is not possible in practice because it will result

in a huge electron density and we know that the distance between the electrons in the atom

is many thousand times larger than the electron itself. Of course one could not

really speak about size of an electron, because it is not a little localized ball

but taking a view if classical picture you can think about it like a localized charge.

David :

Let me know if there are any questions.

David :

and do not forget that the electric field inside conductor is zero simply because if it is not zero the electrons will move around up until the electric field becomes zero. and now if there is an excess charge inside the conductor then the electric field cannot be zero, so tout get a contradiction to this key principal.


OK, but I don't follow the last part. When you say "electrons will move around until the field is zero" how does this work? Do you mean the positive and negative charges equalize each other and the field becomes zero?


but it's the positive and negative charges that create the field in the first place so that doesn't seem right

David :

Imagine there is nonzero electric field inside, OK? hence if there is an electron inside this field it will move, correct? simply because there is a force acting on it.

David :

Yes all charges must equalize each other, this does not mean however that the net charge is zero

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