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Homework Help: Derive Electrostatic Force from Coulomb's Law.

  1. Aug 8, 2012 #1
    1. The problem statement, all variables and given/known data

    I should derive

    [itex]\vec{F_{q}} = \frac{-q'^{2}}{4∏ \epsilon_{0}} \frac{r'/a}{(r'^{2} - a^{2})} \hat{r}[/itex]

    from

    [itex]\vec{F_{q''q'}} = k\frac{q' q''}{\left|\vec{x'} - \vec{x''}\right|^{2}}[/itex]

    2. Relevant equations



    3. The attempt at a solution

    I know that [itex] q'' = -q' \frac{a}{r'} [/itex]

    and [itex] r'' = \frac{a^{2}}{r'} [/itex]


    so, I substituted these. but I can't seem to arrive at the correct formula.
     
  2. jcsd
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