Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: A Polarization Problem

  1. Aug 24, 2006 #1
    I'm trying to teach myself polarization and dielectrics by doing problems, but it's not going as well as I'd hoped. Here's the first problem that I got stuck on:
    A round dielectric disc of radius R is statically polarized so that it gains the uniform polarization P, with the vector P lying in the plane of the disc. Find the strength E of the electric field at the center of the disc if d << R. ​
    I thought that since the disc is polarized along its plane, there would be a charge density [tex]\sigma[/tex] on one half of it, and a charge density of [tex]-\sigma[/tex] on the other half of it. I wasn't sure if [tex]\sigma = P[/tex], but I set them equal anyway. I also wasn't sure if [tex]\sigma[/tex] is uniform along each half-surface, but I did that anyway. Then I thought that a uniform polarization vector means that the whole surface is charged up unformly, which means no net electric field at the center.

    I realize this is going to sound silly, but I have no idea how I'm supposed to solve this problem. Where am I supposed to start?
     
  2. jcsd
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook

Can you offer guidance or do you also need help?
Draft saved Draft deleted