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Homework Help: Magnetic flux of Earth

  1. Oct 25, 2008 #1
    Magnetic flux!!!!

    1. The problem statement, all variables and given/known data
    Find the flux of Earth's magnetic field of magnitude 5.00 10-5 T through a square loop of area 40.0 cm2 for the following:
    (a) when the field is perpendicular to the plane of the loop

    (b) when the field makes a 20.0° angle with the normal to the plane of the loop

    2. Relevant equations

    flux = BA cos theta
    where A is the area and B is the magnetic field

    3. The attempt at a solution
    on the first one i just multiplied 5e-5 by .4 and i got 2.0e-5... and it was wrong and i have NO idea why

    the second one i just used the answer i got previously (obviously wrong) and multiplied it by cos of 20... red x
  2. jcsd
  3. Oct 25, 2008 #2
    Re: Magnetic flux!!!!

    You have to convert cm^2 to m^2 in the correct way
  4. Oct 25, 2008 #3
    Re: Magnetic flux!!!!

    the correct way? its not directly proportional?
  5. Oct 25, 2008 #4
    Re: Magnetic flux!!!!

    It's directly proportional, but not with the proportionality constant you think!

    You seem to think that 40 cm^2 equals 0.4 m^2. That's not true!
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