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!

Homework Help: The work required for adding a charge to an infinite charge distribution

  1. Feb 11, 2008 #1
    1. The problem statement, all variables and given/known data

    Find the energy required to add an additional charge to the chain
    in the limit where the total number of charges approaches infinity.

    So, I have a equidistant linear charge distribution like + - + - + -..... where the total number of charges approaches infinity. The charges are being brought from an infinite distance to there spot in the charge distribution.

    What is the energy required to add a charge on to the "end" of it?

    2. Relevant equations

    Electric force = k(Q1Q2)/d^2
    work = Integral of (Fdot Dr) from path begin to path end

    3. The attempt at a solution

    I wish I could more here, but its one of these problems that I can't set up, so I can't really give an attempted solution but here are my thoughts.

    (backed up by nothing but my intuition)

    It will be a finite number as most of the force due to charge distribution will cancel out.

    It will be close to the amount of energy required to add a charge to a single charge distribution because of the cancellation.

    Any direction would be much appreciate.
    Last edited: Feb 11, 2008
  2. jcsd
  3. Feb 11, 2008 #2


    User Avatar
    Science Advisor

    Use potential. The work equals q V.
    V is an infinite sum of alternating sign with terms like 1/n.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook