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Homework Help: Electric charges/electric fields

  1. Jan 27, 2010 #1
    1. The problem statement, all variables and given/known data

    Two electric charges are separated by a finite distance. Somewhere between the charges, on the line connecting them, the net electric field they produce is zero.

    1) Do the charges have the same or opposite signs? Explain
    2) If the point of zero field is closer to charge 1, is the magnitude of charge 1 greater than or less than the magnitude of charge 2? explain

    2. Relevant equations

    3. The attempt at a solution
    I know for number 1 the charges are the same and that for number 2 it is less. However, I just wanted to clerify whether my thinking process is correct for my reasoning.
    For 1, I think it is the same charge because of the zero magnitude. B/c of zero mag, this means that there are like charges "repelling" each other?
    For 2, I think it is less b/c I think that the magnitude of 2 is greater, thus have a stronger "pull" on the point.
  2. jcsd
  3. Jan 27, 2010 #2
    for two you are correct. if the magnitude on one side is higher, the point will have to be further away from that.

    And for question one, I would describe it as follows. You can think of the sign of a charge describing whether it pushes or pulls. If you have two positive charges on opposite sides of your point of interest. both will be pushing and cancelling out. However, if you have a pushing charge on one side and a pulling on the other. The pulling charge will pull in the same direction that the pushing charge will push.
  4. Jan 27, 2010 #3
    thanks so much for your help!
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