# Neutral conductor and charged insulator brought near each other

What happens when a charged insulator is placed near an uncharged neutral metallic conductor? I know it attracts each other because of charging by induction (electrons redistribute). But would the redistribution of electrons in the metal result in a net electric field inside the conductor or no net electric field? I'm curious to know what and why.

• Can you narrow down what part of the general theory of electric fields in conductors is unclear to to? Mar 31, 2019 at 19:45
• Related question: Metal Sphere in a Uniform Electric field Mar 31, 2019 at 19:50

## 1 Answer

The answer is that no matter how the charges in the insulator are arranged, the electric field inside the conductor will still be zero. Imagine an insulator, which only contains a single electron. If placed above a conductive plate, the positive charges in the conductor will be attracted to it. The negative charges in the conductor will be repelled.

Now apply Gauss' law to a region inside the conductor (green box). Since all the charges will have rushed to the surfaces in response to the electron, the center will contain no charges. If no charges are enclosed, there will be no electric field at its surface.

None of this changes if more electrons are added to the insulator or if their spatial distribution changes. This will cause the charges at the surface of the conductor to rearrange themselves, but there still won't be any inside the conductor. The field there remains zero.