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Homework Help: Electric forces and charges

  1. Oct 3, 2012 #1
    1. The problem statement, all variables and given/known data
    Find the magnitude and direction at the midpoint of two point charges q1=20nC and q2=-40nC

    2. Relevant equations
    How can we answer the question if we aren't given the distance?

    3. The attempt at a solution
    Do I solve in terms of x for distance and use the formula F=K(q1q2)/r^2?
  2. jcsd
  3. Oct 3, 2012 #2


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    Staff: Mentor

    Welcome to the PF.

    Are you sure that you are not given a separation distance? You would need that in order to calculate the resulting E field...
  4. Oct 3, 2012 #3

    Doc Al

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    Staff: Mentor

    Magnitude and direction of what? The electric field?

    Is there a diagram to accompany this problem?

    Seems like that would be a key piece of information.

    You could do that, but my guess is that they meant you to have the distance. Seems too odd to give you the charges but not the distance between them.
  5. Oct 3, 2012 #4


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    Staff Emeritus
    Science Advisor
    Homework Helper
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    Was there a figure that accompanied the problem? Perhaps the needed information is on there.
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