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Homework Help: EMT problem

  1. Oct 11, 2012 #1
    Q. A 30 cm by 40 cm rectangular loop rotates at 130 rad/sec in a magnetic field 0.06Wb/metre sqre normal to the axis of rotation. If the loop has 50 turns, determine the induced voltage in the loop ?

    Attempt !

    V(induced) in 1 turn = ∫(u X B).dS

    my vector u will be ρω in a∅ direction but i am unable to understand the direction of magnetic field what does it mean by direction perpendicular to axis of rotation ?
  2. jcsd
  3. Oct 11, 2012 #2


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    Staff: Mentor

    It means that the magnetic field goes straight through the loop. Say that the loop's axis of rotation is the x direction, then the magnetic field could be in the y or z direction.
  4. Oct 12, 2012 #3

    rude man

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    I think it would be easier to use Farady's law of induction which equates emf to rate of change of magnetic flux.
  5. Oct 12, 2012 #4
    but then if i am considering the direction of rotation to be A∅ wouldn't both the directions Aρ
    and Az will be perpendicular to it !
  6. Oct 12, 2012 #5
    how should i use faraday law in this the conductor position is changing ! wouldn't the faraday law equation result in the equation i have used in the end !
  7. Oct 12, 2012 #6

    rude man

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    Yes, the conductor position is changing. That's what makes the magnetic flux change, since flux = B dot area where B and area are vectors ...

    Yes, yopur equation is tantamount to farady's law. i just meant that using flux = B x A is easier ...
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