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Homework Help: Faraday's Law of Induction and Current

  1. Mar 12, 2009 #1
    1. The problem statement, all variables and given/known data

    A 22.0-cm-diameter coil consists of 20 turns of circular copper wire of 2.6 mm in diameter. A uniform magnetic field, perpendicular to the plane of the coil, changes at a rate of 8.65 x 10-3 T/s. Determine (a) the current in the loop, and (b) the rate at which thermal energy is produced.

    2. Relevant equations
    V = NBA / t
    R= pl/A

    l = N*2*pi*diameter of coil
    A = pi*(radius of wire)2

    I = V/R

    3. The attempt at a solution

    I understand the part (a)... sort of. Tell me if I did it something wrong.

    V = NBA / t
    V = (20)(8.65 x 10-3 T/s)(pi*(.0013 m)2) = 9.19 x 10-3 V

    R = pl/A
    R = (1.72 x 10-8)(20*2*pi*.22 m)/ (pi*(.0013 m)2) = 8.96 x 10-2 ohms

    I = V/R
    I = 9.19 x 10-3 V / 8.96 x 10-2 ohms = 1.03 x 10-5 A

    Part (b) I don't understand. I don't know what I'm finding.
  2. jcsd
  3. Mar 12, 2009 #2


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    Homework Helper

    the rate at which thermal energy is produced.
    It is power and is found by P=I^2*R.
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