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Homework Help: Ring of Charge-how to maximize the Electric Field

  1. Oct 1, 2009 #1
    Ring of Charge--how to maximize the Electric Field

    A thin nonconducting rod with a uniform distribution of positive charge Q is bent into a circle of radius R. The central perpendicular axis through the ring is a z-axis, with the origin at the center of the ring.

    (c) In terms of R, at what positive value of z is that magnitude maximum (of the Electric Field)?

    After going through the integration, the equation for a ring of charge is

    k*(Qz / (z2+R2)3/2))

    Edit: So, with some help, I realized that to maximize the function, I'd have to differentiate...
    But what am I differentiating with respect to? z? r? And I know k is a constant; are everything else non-constants?
    Last edited: Oct 1, 2009
  2. jcsd
  3. Oct 2, 2009 #2


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    Re: Ring of Charge--how to maximize the Electric Field

    You're looking for the value of z which maximizes the function, while the size of and charge on the ring are constants.
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