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Calculating magnetic flux of a rod

  1. Mar 27, 2017 #1
    1. The problem statement, all variables and given/known data
    B = 0.02T
    L = 40 cm
    w = 10 rad/s
    a: Electromotive force between O and C = ?
    1 - Copy.jpeg

    b: If electromotive force is the same - so what is the velocity?
    2.jpeg


    I found 2 ways of solution. See "3. The attempt at a solution"


    2. Relevant equations
    φ = BA
    ε = -dφ(t)/dt

    3. The attempt at a solution
    So I found 2 ways:
    1. What every one would do - by Electric:
    sol.jpeg

    2. By the magnetic flux. But wait - There is no area.
    So I found that if I would take in problem a the area of what the rod had passed (part of a disc) I would get the exact solution.
    1 - Copy.jpeg
    1.jpeg

    For problem b if I would take the area of a triangle I will get the solution too.


    My question - Why does the second way is also true? How can it be explained (For both problem a and b)?

    Thanks a lot!
     
    Last edited: Mar 27, 2017
  2. jcsd
  3. Mar 27, 2017 #2
    Is that a line or a rod? The way the picture is presented it doesn't look like there is any flux, let alone a change in flux. Did you give us the entire problem statement?
     
    Last edited: Mar 27, 2017
  4. Mar 28, 2017 #3
    I gave you the entire statement.
    And you are right, as I wrote there are no magnetic flux because there is no area.

    I meant that Ive found that we can take an imaginary area and it will give us the same solution. ( See picture -0.016 V)

    My questions are why is it true and how can it be explained?
     
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