Why does the inside of a conductor have the same electric potential everywhere?

[lifeiseasy]

My teacher said so, but I just don't understand why. Is it because of the free movement of electrons inside the conductor?

 

[Hootenanny]

My teacher said so, but I just don't understand why. Is it because of the free movement of electrons inside the conductor?

That statement is only true if the conductor is in equilibrium.

 

[sokrates]

Think of it this way: If the potential wasn't zero everywhere in the conductor, due to the many free electrons in a good conductor, there would be charge flow against this potential gradient and the gradient would vanish very quickly.

But as Hootenanny pointed out, this is true only for equilibrium. In an electronic device where you want steady state current flow, the conducting channel is always out-of-equilibrium and there's a potential gradient across it.

 

[Bob_for_short]

My teacher said so, but I just don't understand why. Is it because of the free movement of electrons inside the conductor?

Yes. If there is a potential difference, it means existence of an electrical field E and the force eE. In a conductor the charges move until their new charge distribution creates a polarisation field compensating the external one.