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Homework Help: Find the Electric Field

  1. Feb 19, 2010 #1
    1. The problem statement, all variables and given/known data
    Consider two point charges placed on a line:



    a) Find the electric field E at the position P *hint: bring + at P. Ep=Ep1+Ep2
    b) Using the above E, find the electric force on the charge q=-1.00uc placed at P.
    c) Check your answer F of (b) by computing directly F.

    2. Relevant equations

    3. The attempt at a solution
    I attempted to solve and with the charge acting on q1, I got 2.25X10^3 N/C. For the charge acting on q2, I received the answer -2.25X10^3 N/C. I figure this isn't correct since I need to use something other than 0 when these are added to figure out part b. Thanks for your help in advance!
  2. jcsd
  3. Feb 19, 2010 #2
    :) you are right this is not zero ..

    hint : remember that the electric field is a vector , and remember that the electric field produced from a positive charge is not the same as the negatice charge, check this figure:

    http://img684.imageshack.us/img684/3059/38165338.jpg [Broken]

    try to draw the electric field vector produced by both the positive and the negative charges , what will you get?
    Last edited by a moderator: May 4, 2017
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