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Homework Help: Electric Field due to a Ring of Charge

  1. Jul 9, 2006 #1
    I've been stuck on this problem for awhile now..

    At what distance along the central axis of a ring of radius R and uniform charge is the magnitude of the electric field due to the ring's charge maximum?

    Now, I know that the equation for this problem is E = [k|qz|] / [(z^2+R^2)^3/2], which is the electric field magnitude of a charged ring. And to get the maximum, you have to find where the first derivative of the equation where it equals zero.

    But when I take the derivative of the equation, I get a complete mess not even close to the answer. Can anyone give me some hints or a push in the right direction? Is my thinking incorrect? Thanks. :)
  2. jcsd
  3. Jul 9, 2006 #2
    It's a straighforward problem, and your approcah is right. If you could just post your work, we can try to help you out.
  4. Jul 9, 2006 #3
    Thanks, confirming that I was going in the right direction was all I needed. I eventually did get the answer, but with some difficultly thanks to my poor algebra skills. :)
  5. Sep 17, 2011 #4
    In this problem we do not know E and we are looking for z correct? I do not know how to deal with this problem of having two unknowns. I am given R but that is all.
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