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Electromagnetic Induction

  1. Mar 5, 2012 #1
    1. The problem statement, all variables and given/known data

    A flat coil of wire has an area of 0.010 m2and contains 100 turns. Initially the coil is oriented so that the normal to its surface is parallel to a downward constant magnetic field of 0.2 T. The coil is then rotated clockwise through an angle of 30oin a time of 0.10 s. What is the average induced emf? (Note: the initial emf is zero)

    a. 0.50 V

    b. 0.45 V

    *c. 0.18 V

    d. 0.25 V

    2. Relevant equations

    emf=-Δ[itex]\Phi[/itex]B/Δt
    [itex]\Phi[/itex]B=N*ABcos(θ)

    3. The attempt at a solution
    emf=-Δ[itex]\Phi[/itex]B/Δt
    emf=-N*AB(cos(θ1)-cos(θ2))/Δt
    emf=-100*0.01m2*.2T(cos(0)-cos(30))/.1s
    emf=2.7x10-2V

    the answer appears to be .18V...can someone tell me why is this? thanks!
     
  2. jcsd
  3. Mar 5, 2012 #2

    I like Serena

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    Hey!

    Nope. I can't tell you why that is.
    Btw, he answer I get is emf=0.27V, so it seems to me you made a mistake with the power of 10.

    In other words IMHO your answer key is wrong!
    The right answer isn't even in there.
    Is it possible you made a typo when typing down the problem statement?

    Anyway, I believe we've given you an answer like this one a couple of times before.
    Where do you get your answers?
     
  4. Mar 5, 2012 #3
    Last edited by a moderator: May 5, 2017
  5. Mar 5, 2012 #4

    I like Serena

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    So where's this one and its "answer"?
     
  6. Mar 5, 2012 #5
    on the first link unit 3>>chapter 14>>lesson 41>> assessments >>answer key >>question 7
     
  7. Mar 5, 2012 #6

    I like Serena

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    Yep. I see it.
    And still no clue why the answer would be wrong.
     
  8. Mar 5, 2012 #7
    Oh well :/
     
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