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Homework Help: Charges in 1D

  1. Jun 28, 2010 #1
    1. The problem statement, all variables and given/known data

    A pair of charges sits on the x-axis, a charge Q1 = +9 nC at the origin and Q2 = +4 nC at x = 5. Assume no other charges are present. All coordinates are in meters.

    At which one of these points is the net electric field equal to zero?

    2. Relevant equations

    3. The attempt at a solution
  2. jcsd
  3. Jun 28, 2010 #2
    Follow up questions:

    What is the potential at x = -5 ?

    How much work is required to move the +4 nC charge (Q2) from its original location at x = 5 to x = 3 ?

    Any explanation would help?
    Thank You
  4. Jun 30, 2010 #3
    The field can be zero at a point only if the fields due to the two charges cancel out at that point.
    In which region can this happen? Left of Q1 / between Q1 and Q2 / right of Q2 ?
    In each region you could draw the field vectors due to each charge & see where they could possibly cancel out.

    Moving on to the follow up questions, do you know the potential due to a charge? And, how work is related to potential ?
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