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Homework Help: Electrostatic Force

  1. Oct 17, 2008 #1


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    1. All variables and given/known data:

    [itex]a = c = 1 \times 10^{-19} C[/itex]
    [itex]b = 2 \times 10^{-19} C[/itex]
    Distance between a&b = b&c = 0.1m (b at origin, a at (0, 0.1) and c at (0, -0.1))

    2. Relevant equations:

    [itex]F = k\frac{|q_1||q_2|}{r^2}[/itex]

    3. The problem that I'm having:

    Am I correct to think that the electrostatic force on b from other charges is at a minimum because the Force will be positive and negative (due to the nature of r ([itex]\pm[/itex] 0.1)) cancelling each other out? :confused:
  2. jcsd
  3. Oct 17, 2008 #2


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    Homework Helper

    Yes, the force on b due to a is "pointing down", and the force on b due to c is "pointing up", and the magnitudes of those forces are equal (from your equation). And so the vector sum of all the forces on b is zero in the situation shown.
  4. Oct 18, 2008 #3


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    I just realised that the radius will be squared hence the negative will also produce a positive force. How does it equal zero then (Surely, it will just equal 2F)? Am I to use another formula or is the electrostatic formula correct to use?
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