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Homework Help: What is the magnitude of the electric field

  1. Jan 21, 2010 #1
    1. The problem statement, all variables and given/known data
    A cat rubs her back on the carpet, and acquires a net charge of -54.1 uC. What is the magnitude of the electric field at a distance 4.01 m from the cat?
    What would the magnitude of the electric field in the previous problem be,
    if the distance from the cat were now tripled?

    2. Relevant equations

    3. The attempt at a solution
    my answer came to 2.86E4 N/C which is wrong.

    obviously i should be able to get the second part once i understand what i am doing wrong in the first part
  2. jcsd
  3. Jan 21, 2010 #2
    You have calculated the force due to the electric field, not the field itself.

    I believe the eq you are looking for is:
  4. Jan 21, 2010 #3


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    it shouldn't :redface: … did you enter 8.5 instead of 8.9?

    (and isn't it 8.988, or just 9.0, anyway?)
  5. Jan 21, 2010 #4
    k so i did

    E=54.1E-6/4*3.14*8.85E-12*4.01^2 and got 2.7E4 N/C which still was wrong. what else did i do wrong?
  6. Jan 21, 2010 #5
    Never mind I got it. i was using the right equation, lol i guess i did just enter a number in wrong. funny cause i did it like 10 times. thanks though tiny-tim
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