1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

E&M simple polarizability question

  1. Jul 12, 2014 #1
    this is a homework problem i realized after posting it. so could a moderator please move this question to the hw section? thanks

    one of Griffiths' example:

    A primitive model for an atom consists of a point nucleus surrounded by a uniform charged spherical cloud of radius "a". Find the atomic polarizability of such an atom.

    (reference equation):

    $$\vec{p}=a \vec{E}$$
    -------------------

    First step:

    the field (produced by the electron cloud) at distance d from the center of a uniformly charged sphere is

    $$E_e=\frac{1}{4\pi \epsilon_0}\frac{qd}{a^3}$$

    ---------------


    so why is that the field produced by the shifted electron cloud?

    ie, how does one go from

    $$E_e=\frac{1}{4\pi \epsilon_0}\frac{q}{a^2}$$

    to..

    $$E_e=\frac{1}{4\pi \epsilon_0}\frac{qd}{a^3}$$

    (where "d" and "a" are not equal)?
     
    Last edited: Jul 12, 2014
  2. jcsd
  3. Jul 12, 2014 #2

    UltrafastPED

    User Avatar
    Science Advisor
    Gold Member

    It's a dipole field.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: E&M simple polarizability question
  1. Simple E&M questions (Replies: 26)

  2. E&M clarification (Replies: 1)

  3. E&M Faraday's Paradox (Replies: 14)

Loading...