In electromagnetism books, such as Griffiths or the like, when they talk about the properties of conductors in case of electrostatics they say that the electric field inside a conductor is zero.
I have 2 questions:
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We know that conductors (metallic) have free electrons which randomly moves in all directions, so how come we can talk about electrostatics which by definition means stationary charges?
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When the textbooks try to show why the electric field inside a conductor is zero they say let us put our conductor in an electric field. What happens then is that there will be an induced surface charge density which consequently induces an electric field within the conductor such that the total electric field within the conductor will be zero. That is perfectly understood, but my problem is the following: the original claim was that the electric field within a conductor is 0, not the electric field after putting the conductor in an external electric field it became zero. I do not understand the logic!
Best Answer
Conductors are defined by the freedom of some of the charges inside to move with little resistance.
So, if there were a non-zero field, what would happen? Answer: some of the free charges move until the field is again zero.
You might be wondering if there are limits to this claim, but a introductory book of that sort is not worrying about extreme situations. In any case, try choosing a simple geometry, make an estimate of the fraction of charges that are free to move and calculate the saturation field.