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Homework Help: Net electric field question

  1. Jul 17, 2006 #1
    Two charges, -16 and +4.1 µC, are fixed in place on the x axis at x = 3.0 m and x = 0 m, respectively.

    a. At what spot along the x axis is the net electric field zero?
    b. What would be the force on a charge of +17 µC placed at this spot?


    I know that the point where this occurs does not occur in between these two charges. But I'm not really sure how to represent this point in Coloumb's Law to find its value.

    Then, after finding this point, I'm not sure if I should just consider the interaction with the charge that is closest to this point, or the interaction with both charges.

    I'll appreciate any direction that will help solve this problem. Thanks.
  2. jcsd
  3. Jul 17, 2006 #2


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    EDIT: Lol..... I thought the part under the line was your signature for some reason. That'll teach me to read.

    For the first part: Is the point to the left or right of both charges? (is x > 3 or x < 0?).

    For the second part.... if the net electric field is zero, how much force is being applied to ANY charge?
  4. Jul 18, 2006 #3
    Draw a diagram and indicate the two charges. Then draw arrows representing directions of fields of both charges in the three regions (x < 0, 0< x < 3 and x > 3). In which region(s) can the arrows cancel?
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