Elektrisch veld in een geleider

Consider a conductor placed in an external electric field. In a conductor, only the electrons are free to move.

The free electrons migrate opposite to the external electric field, accumulating at one end of the surface.

Consequently, the other end of the surface has a lesser number of electrons and so gains a net opposite surface charge, thus polarizing the conductor.

Due to the accumulation of surface charges, an internal electric field is developed opposite the external field.

As the charges continue to move, the internal field magnitude increases until it equals the external field.

The conductor now reaches a steady state known as electrostatic equilibrium, and the charges do not move anymore.

In this condition, the net field at all the points inside the conductor, which is the sum of the external and the internal fields, vanishes.

From Gauss' law, zero electric fields imply no net charge enclosed inside a conductor.