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Homework Help: Exchange between coils

  1. Mar 3, 2010 #1
    1. The problem statement, all variables and given/known data
    A strong electromagnet produces a uniform magnetic field of 1.60 T over a cross-sectional area of 0.200 m2. We place a coil having 190 turns and a total resistance of 21.0 around the electromagnet. We then smoothly reduce the current in the electromagnet until it reaches zero in 20.0 ms. What is the current induced in the coil?

    2. Relevant equations
    B = (mu)*I/2*Pi*r for a wire
    B = (mu)*n*I for a coil
    Flux: P=BA
    V = (Bf-Bi)*A/(tf-ti)
    V = (mu)*n*A*(If-Ii)/(tf-ti)

    3. The attempt at a solution
    V = (0-1.6)*.2/.02 = 16
    I = 16/21 = .7619
    (which is off by orders of magnitude)

    I knew that way wouldn't work because it was too simple and didn't include the number of turns but tried it anyway at the request of my instructor
    How do I set this up???

  2. jcsd
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