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Homework Help: Electric Potential of a Circular Rod

  1. Jan 31, 2008 #1
    http://img136.imageshack.us/img136/7548/44938265by3.jpg [Broken]

    Okay I am not sure how to do this problem without having lambda. I talked to my professor and he said I don't need lambda.

    I know that finding the potential due to a continuous charge is

    dV = (Kdq)/r

    But in this case, I am not sure how to do it. What is dq?

    Can someone please explain to me how do I approach doing this problem.
    Last edited by a moderator: May 3, 2017
  2. jcsd
  3. Feb 1, 2008 #2
    Hmm. I haven't figured out how to do the problem with a simple trick, which it sounds like your professor made one in there.

    What is the charge density really? Charge per unit length. You can get the charge density and then integrate like normal. Though the integral is not entirely trivial to set up correctly, so there probably is some kind of trick we are missing.
  4. Feb 1, 2008 #3
    you need the surface charge. You should have something like dV=bda; where b=surface charge of the tube. from there you input it back into to find V=k/r. at least that is how I would approach the problem.
  5. Feb 1, 2008 #4
    I am confused.
  6. Feb 1, 2008 #5


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    Homework Helper

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