# Homework Help: Polarization charge density

1. Sep 17, 2013

### Dassinia

Hello,
1. The problem statement, all variables and given/known data
We use an accelerator to uniformly implant electrons in a block of lucite, its surface is 25 cm², thickness 12mm.
The current of the electron beam is 0,1 µA and the implantation takes 1s.
The electrons are "trapped" in a layer of uniform density of 2mm thickness whose center is at 6 mm of the block surface. The two large surfaces have same potential V=0.

- Find the polarization charge density ρp in each of the three regions of the block.
- Find the polarization charge density of surface σp over the two large surfaces of the block.
2. Relevant equations
ρ= . D
DoE+P
Po XeE
σp= P.n^
3. The attempt at a solution

I'd say that outside the layer where the electrons are ρp =0
And I am really really stuck ..
I have to return this before the end of tomorow, and i'm not getting any of this.. I've read the course notes a hundred times
Thanks !

Last edited: Sep 17, 2013