# Homework Help: Quick question, eletric field of a conducting sheet of charges

1. Feb 24, 2013

### kougou

Hi

one quick question about the electric field of a conducting sheet of charges.

When you given a horizontal sheet of conductor with uniform distributed charge on its surface,will there be any electric field on the top AND on the bottom of the sheet?

How is that different from a horizontal sheet of insulator (or dieletric material) consist of uniform surface charge? The eletric field will also be on the top AND the bottom of the sheet?

2. Feb 25, 2013

### Simon Bridge

The electric field extends to the surface of the sheet on both sides - where, classically, it stops. The electric field exactly at the surface is zero though.

It is no different from the exact same distribution of charge across an insulator or a dielectric. Field lines start (or end) on charges.

However, a thick insulating sheet with a "uniform charge" may have the charge distributed uniformly through it's thickness - an option not available for a conductor - which has to carry all it's charge on it's surface.

Bear in mind that these are idealized teaching examples designed to get you used to using the math. It's a good idea not to draw very general conclusions from them.