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Homework Help: Electric Field of a Uniformly Charged Ring

  1. Jan 23, 2010 #1
    1. The problem statement, all variables and given/known data
    A uniformly charged ring of radius 8.1 cm has a total charge of 118 micro Coulombs. The value of the Coulomb constant is 8.98755e9 N M^2/C^2. Find the magnitude of the electric field on the axis of the ring at 1.15 cm from the center of the ring. Answer in units of N/C.

    2. Relevant equations
    F= k Qq/ r^2
    E= kq/r^2

    3. The attempt at a solution
    I tried subtracting 1.15 cm from 8.1 cm for "r" and plugged that "r" value in the F equation but that answer is wrong. By axis , do they mean horizontally (as in along the diameter) or vertically?
    Last edited: Jan 23, 2010
  2. jcsd
  3. Jan 23, 2010 #2
    do i just do the pyth. theorem to solve for "r" ( square root of 8.1^2 + 1.15^2)?
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