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Homework Help: Confused by the fractions in the parenthesis

  1. Aug 26, 2010 #1
    1. The problem statement, all variables and given/known data

    Given: see attachment

    Five additional electrons are placed at the origin. What is the electric field now.

    2. Relevant equations

    Electric field equations of E=q/(4pi*Eo*r^2)

    3. The attempt at a solution

    I am wondering if the electric field would just be 50% higher because of adding five electrons. However I am somewhat confused by the fractions in the parenthesis. I know that the electric field is going to be a summation of the charges relative to the distance from a point. I am just unsure how to apply that thought in this case due to my misunderstanding of those fractions in the parenthesis. Thanks!
     

    Attached Files:

  2. jcsd
  3. Aug 26, 2010 #2

    kuruman

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    Re: Electrostatics

    If all you had is five electrons at the origin, what would be the electric field vector as a function of r? If you know the answer, then add that field to the given one and you're done. That's how superposition works.
     
  4. Aug 26, 2010 #3
    Re: Electrostatics

    I think I see where u are coming from. So I basically take the 5e/(4pi*ep*r^2) and add it to the original vector?
     
  5. Aug 26, 2010 #4

    kuruman

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    Re: Electrostatics

    Yes, add it with unit vector r-hat tacked on it.
     
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