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Electric Fields and rods

  1. Sep 5, 2005 #1
    Here's my problem:

    Three 10-cm-long rods form an equilateral triangle. Two of the rods are charged to + 10 nC, the third to -10 nC. What is the electric field strength at the center of the triangle?

    Answer in back of book: 1.08 * 10^5 N/C

    By looking at the corresponding section, it gives the formula for the electric field strength in the plane that bisects a charged rod as:
    Q/(4*pi*e_0*r*sqrt(r^2 + (L/2)^2)),
    where e_0 is given to be 8.85*10^-12.

    I thought that you would add the vertical and horizontal components of the 3 electric fields in the center due to each rod to get the net electric field. After some calculations, I get that the final answer should be 2 times the formula I gave above, but this does not give me the correct answer. What am I doing wrong? Please respond, thanks!
  2. jcsd
  3. Sep 6, 2005 #2
    Nevermind, I got it.
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