# Homework Help: Polarization of materials

1. Sep 23, 2010

### agrianne

1. The problem statement, all variables and given/known data
Show that the polarization of a material is P=Nqx where x is the displacement between the center of the electron cloud and the atomic nucleus.

2. Relevant equations
P=Nqx is given and I went ahead and subbed (q/m) * E[1/(w0^2 - w^2)] for x.

3. The attempt at a solution
After that I'm kind of stuck. I tried some basic manipulation with P=E($$\epsilon$$0-$$\epsilon$$), but I'm just shooting in the dark here. I feel like I'm missing some basic information that makes this a simple question.

2. Sep 23, 2010

### gabbagabbahey

Are you given any other info? Is this exactly the way the question is stated?

To me, this sounds like you are supposed to assume that each atom is modeled by a positively charged nucleus, surrounded by a spherically symmetric elecron cloud and that the material contains $N$ atoms per unit volume. But that's just an educated guess.

Huh?

Reading the question, I thought you were being asked to prove that P=Mqx, not that you are supposed to take it as given. Where is x=(q/m) * E[1/(w0^2 - w^2)] coming from?

3. Sep 24, 2010