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Homework Help: Ignore this figured it out!

  1. Dec 2, 2009 #1
    didn't convert cm to m

    1. The problem statement, all variables and given/known data
    A solenoid has 10 turns/cm and carries a 4-A current. A circular loop with 5 turns of area i cm^2 lies within the solenoid with its axis at 37 degrees to the axis of the solenoid. Find the magnitude of the average induced emf if the current increases by 25% in .1 seconds.

    2. Relevant equations
    emf = N * d(flux)/dt
    flux = B dot da

    3. The attempt at a solution
    I'm confused about why the solenoid's area is not given. How is the loop's area relative to the solenoid's area not relevant?

    Here's what I tried:
    emf = N d(flux)/dt
    = (N * A * cos(theta)) * (B(final) - B(initial))/(deltaT)
    and B for a solenoid is sol2.gif

    so (N * A * cos(theta) * μ * n) * (I(f) - I(i))/(deltaT)
    then ( 5 * 8 * cos(37) * 4 * pi * 10^-7 * 10) * (4 * 1.25 - 4)/ .1=4mV

    the answer is in microvolts, so i'm obviously doing something completely wrong
  2. jcsd
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