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Homework Help: In need of dire electrostatics help. Please check my work, provide insights, etc.

  1. Feb 8, 2010 #1
    Here's a problem.
    A house fly accumulates 3.0 (10)^-10 of positive charge as it flies through the air. What is the magnitude of the electric field at a location 2.0 cm from the fly?

    Here's what I think.
    I should use the equation E = kq/d^2. I am trying to find E.
    k = 9.0 (10)^9
    q = 3.0 (10)^-10 C
    d = 0.02
    So after plugging in the numbers... I arrive at the value of 6750 N/C.

    I thought that q in this case was supposed to be a test charge. And the only charge I have is most definitely the source charge. Am I wrong? Does this make a difference?

    Any help would be greatly appreciated.
  2. jcsd
  3. Feb 8, 2010 #2


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    Gold Member

    Seems good to me. If they ask for the vector E, you should mention its direction, if the magnitude is asked, then I think you're right.
  4. Feb 8, 2010 #3
    Okay, great. Thank you! I might have someone look over another question or two... so stay tuned! Haha
  5. Feb 8, 2010 #4
    Okay, nevermind. I think I actually got all the rest of them!
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