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Homework Help: Induced Emf in a Rectangular Coil

  1. Mar 15, 2012 #1
    1. The problem statement, all variables and given/known data
    A rectangular coil of 90 turns has dimensions of 22 x 65 cm and is located in a uniform 1 T magnetic field. In 1.7 s, the plane of the coil is rotated from a position where it makes an angle of 19° with the magnetic field to a position where it makes an angle of 64°. Calculate the average emf induced in the coil.

    2. Relevant equations

    emf= -N*(d[itex]\Phi[/itex]/dt)

    3. The attempt at a solution

    So I calculated the change in flux to be: (B*A*cos(90-64))-(B*A*cos(90-19)=B*A*(cos(26)-cos(71))

    I then calculated emf.
    emf= - ((90 turns)*(1 T)*(0.22m*0.65m)*(cos(26)-cos(71)))/1.7 s = -4.34 V
    This is wrong. I then entered the absolute value, which is also incorrect.
  2. jcsd
  3. Mar 16, 2012 #2


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    Science Advisor
    Homework Helper

    Hi SgtMousse! :smile:
    looks ok :confused:

    have you tried 4.3 V, since it should be two significant figures ?​
  4. Mar 16, 2012 #3
    Apparently my answer was correct, even though it was marked wrong. I just checked my online homework site, and they marked it correct. They must have had it wrong before. Thanks anyway!
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