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Magnetic Field Protractor

  1. Apr 11, 2016 #1
    1. The problem statement, all variables and given/known data

    Screenshot 2016-04-11 at 6.png

    2. Relevant equations

    R = ρ (l/A)
    I = ε/R
    s = rθ
    Magnetic flux = Integral(B ⋅ dA)

    3. The attempt at a solution

    I managed to solve parts (a) and (b) independently. Here is my work for those two parts:

    20160411_182020.jpg

    My real issue is with part (c) which uses the answers from (a) and (b). I have absolutely know idea how to solve part c, except that it involves in some way the formula Magnetic flux = Integral(B ⋅ dA)
     
  2. jcsd
  3. Apr 11, 2016 #2

    TSny

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    Be careful with converting mm2 to m2.

    So far, you have not mentioned the basic law of electromagnetism that accounts for the induced current in the circuit.
     
  4. Apr 12, 2016 #3
    Yes, You're right. That law goes as follows:

    ε = - the rate of change of flux (sorry I do not know how to write this in the proper notation)

    And the induced current is found, simply, through Ohm's law: ε = iR

    So how can I, with this, go about part (c)?
     
  5. Apr 12, 2016 #4

    TSny

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    How do you find the rate of change of a quantity. What mathematical operation is involved?
     
  6. Apr 12, 2016 #5
    Take the derivative. So I can take the derivative of part (b). But theta needs to be expressed in terms of the time, t?
     
  7. Apr 12, 2016 #6

    TSny

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    Yes.
     
  8. Apr 12, 2016 #7
    Thank you!
     
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