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Homework Help: Gauss's Law Questions

  1. Sep 29, 2010 #1
    I was searching the forums and I found someone asking the same question a while back, but i am totally confused, I thought I was understanding this stuff up to this point.

    http://answers.yahoo.com/question/index?qid=20100928212107AAwXTlT&r=w [Broken]

    I posted and wrote up the whole problem on yahoo answers.

    If someone could break down this problem and make it easier for a very slow person to understand it would be greatly appreciated!

    Last edited by a moderator: May 4, 2017
  2. jcsd
  3. Sep 29, 2010 #2


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    Hi imzack and welcome to PF. It would be easier if you posted the problem here. Anyway, for part (a): Can you use Gauss's Law to find the electric field at a point inside the sphere?
  4. Sep 29, 2010 #3
    yea, and just got the answers, but i didnt know and didnt understand how they got to them, is someone could break it down it would be most appreciated!!

    An early (incorrect) model of the hydrogen atom, suggested by J.J. Thomson, proposed that a positive cloud of charge +e was uniformly distributed throughout the volume of a sphere of radius R, with the electron (an equal magnitude negatively charged particle -e) at the center.
    A) using Gauss's law, show that the electron would be in equilibrium at the center and, if displaced from the center a distance r<R, would experience a restoring force of the form F=-Kr, where K is a constant.
    B) Show that K=(ke)(E^2)/R^3
    C)Find an expression for the frequency f of simple harmonic oscillations that an electron of mass me would undergo if displaced a small distance (<R) from the center and released.
    D) Calculated a numerical value for R that would result in a frequency of 2.47*10^15 Hz, the frequency of the light radiated in the most intense in the hydrogen spectrum.

    answer is



    <a href="http://tinypic.com?ref=14ma06o" target="_blank"><img src="http://i53.tinypic.com/14ma06o.jpg" border="0" alt="Image and video hosting by TinyPic"></a>

    and thank you for your welcome!!!
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