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Homework Help: Problem concerning magnetism. Please help

  1. Oct 24, 2004 #1
    Problem concerning magnetism. **Please help

    A 13 ohm square loop, whose dimensions are 4m x 4m, is placed in a unifrom .14T magnetic field that is directed perpendicular to the plance of the loop.

    The loop, which is hinged at each vertex, is pulled as shown (it is being tugged from the left and right sides, in opposite directions. the square is set a bit on its side, so it looks like a diamond) until the separation between points C and D (points C and D are at the top and bottom corners of the square... remember it is tilted like a diamond) is 2.6m. The process takes .14 secs.

    What is the average current generated in the loop?


    Here is how i approached the problem.

    I know that I = E/R. And and i know what R is, and im looking for I, so i need to solve for the induced emf E.

    E = (change in flux)/(change in time)

    E = (4m * 4m * .14T)/(.14 secs) = 16 V.

    I = 16/13 = 1.230769 As. This is incorrect however, according to my hw service. I know i am doing something wrong, but i cant put my finger on it. The 2.6m that the square is stretched must play a part in the problem, right? Am i calculating the flux incorrectly?

    Please help guys.
  2. jcsd
  3. Oct 24, 2004 #2
    eek... i didnt think this problem was that difficult. no one has any idea?
  4. Oct 25, 2004 #3
    as you said, change in flux...you just have the initial flux...what about the flux when the top and bottom are 2.6 m away? You can draw this and see that there are some triangles that you can use to find the area
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