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Homework Help: Current through a coil in a magnetic field

  1. Sep 13, 2009 #1

    A coil of 90 turns, of resistance 6 ohm and area 28 cm² moves from a
    uniform magnetic field of 0.02 Tesla to one of 0.42 Tesla in 3.0 second.
    What average current flows in the wire (in amp) ?

    Relevant equations:

    EMF= (Area * Rate of change of magnetic flux) * Number of turns

    I = EMF/Resistance

    Attempted Solution:

    EMF= ((0.28^2) * ((0.42-0.02)/3)) * 90 turns = 3.36

    I = EMF/Resistance = 3.36/6 = 0.56 amps (i believe this is correct)

    however answer given is 0.0056 amps where am I missing this factor of 100?
    Last edited: Sep 13, 2009
  2. jcsd
  3. Sep 13, 2009 #2


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    Staff Emeritus
    Science Advisor
    Gold Member

    [tex]28\;cm^2 \neq 0.28\;m^2[/tex]
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