Electric field inside the conductor is zero. That means there is no electric force on electrons inside. Then how do free electrons move from atom to atom in random direction? What is the reason of this random movement? Sorry if this question looks very basic.
Electromagnetism – If Electric Field Inside a Conductor is Zero, Why Do Free Electrons Move?
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Related Solutions
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.
The "NET" Electric field inside a "conductor" is always zero as you have said.This is basically due to the presence of a lot of free electrons in the conductor.
Let us consider a conducting plate kept in a uniform electric field perpendicular to the plane of the conductor as shown.
The electric field exerts a force F=-eE on the the free electrons of the conductor pulling the electrons to the left side ( to the direction opposite to the electric field) of the conductor creating negative charge accumulation on that side. This in-turn creates a positive charge accumulation on the other side of the conductor. This accumulation starts to create an electric field opposite in direction to the existing electric field ( that is the new electric field opposes the already existing one). This accumulation increases and so do the opposing electric field. This continues until both the electric field become equal in magnitude. So the new opposing electric field completely cancels out the already existing on (only inside the conductor). So the net electric field in inside the conductor becomes 0. All this happens basically in nano seconds. So, the conductor isn't affected by any new electric field coming across it as it is cancelled out instantly.
So, Getting to your question, the excess charges creates an electric field inside the conductor.Now,the mobile electrons rearranges as you have said to create another electric field which will totally cancel out the existing electric field inside the conductor. Its the "net electric field" that will be zero inside a conductor.
Best Answer
The electric field is only $0$ in the electrostatic case. That is, the field is $0$ when no electrons are moving.
Suppose it was not $0$. Electrons would feel a force and move in that direction. This reduces the electric field. They move until it is $0$.
To see why the movement reduces the field, consider this example. Suppose a wire has a + charge at one end and a - charge at the other. This sets up a field from + to -. Electrons have a - charge, and so feel a force in the opposite direction of the field. That is, they are attracted to the + charge, and repelled by the - charge. Electrons flow away from the - end and toward the + end until they have balanced the charges.