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Homework Help: Point Electrical Field

  1. Mar 12, 2007 #1
    1. The problem statement, all variables and given/known data

    at a distance of 1.0 m from a point charge, the electric field is 40 J/C. What is the electric field at a distance of 2.0 m from the point charge?


    3. The attempt at a solution

    so, i understand that the elecric field should be = charge/distance(squared).

    so I did:
    40/(2^2) = 10 J/C

    Is this correct or am i missing something? thanks
     
  2. jcsd
  3. Mar 12, 2007 #2
    Are you sure it's J/c? Isn't that volts? Shouldn't it be N/c?

    http://www.glenbrook.k12.il.us/GBSSCI/PHYS/CLASS/estatics/u8l4b3.gif [Broken]

    Excuse me if I'm blabbering, I'm just trying to look smart with my less than a year's worth of physics:biggrin:
     
    Last edited by a moderator: May 2, 2017
  4. Mar 13, 2007 #3
    im no craque at physics, but all my options are in J/C.
     
  5. Mar 14, 2007 #4
    [tex]E=\frac{Kq}{r^2}[/tex]
    [tex]k=\frac{1}{4\pi \epsilon}=9x10^9N[/tex]
    Find q, and then use the above equations to find E at r=2.
     
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