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Homework Help: Induced emf

  1. Mar 12, 2005 #1
    A 7.2 cm diameter loop of wire is initially oriented perpendicular to a 1.3 T magnetic field. It is rotated so that its plane is parallel to the field direction in .20 s. What is the average induced emf in the loop?

    A = πr2

    A = π*.001 = .004 m

    ФB = BA

    = (1.3T)(.004m) = 5.2E-3 Wb

    ФB / t = 0-5.2E-3 Wb / .20 s

    = -2.6E-2 Wb/s

    € = -(1)( -2.6E-2 Wb/s)

    = 2.6E-2 V

    I think i messed up in my area of my formula. can someone help me out here.
  2. jcsd
  3. Mar 12, 2005 #2
    I don't see any trig functions there... because the loop is rotated, there has to be a change in the dot product of the vectors.

    Remember that A . B = |A| |B| cos theta
  4. Mar 12, 2005 #3
    Now that I think about it - can't you just take BA/t and then times it by 1/root(2) to get the root mean square voltage.
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