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Homework Help: Why there's a reading on the voltmeter connected to coil Q?

  1. May 1, 2017 #1
    1. The problem statement, all variables and given/known data
    The current in coil P is constant. An iron rod is inserted into coil P. Coil Q is placed next to P with a voltmeter connected to it. Explain why, during the time that the rod is moving, there is a reading on the voltmeter connected to coil Q

    2. Relevant equations
    emf=-Dphi/dt

    3. The attempt at a solution
    I believe that the Iron rod will first be magnetised and then the magnetic lines originating from Iron will cause a change of flux in coil Q.
     

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  2. jcsd
  3. May 1, 2017 #2

    CWatters

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    Find the equation for the magnetic field produced by a coil/solenoid. What does it depend on? What is changing in this set up?
     
  4. May 1, 2017 #3
    The equation is B=uIn, and none of the u and n are constant. Current is changing due to change of flux inside the coil P as Iron screens the magnetic lines of P?
     
  5. May 1, 2017 #4

    CWatters

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    The number of turns n is constant, as is the length l.

    What do you know about the relative permeability u?
     
  6. May 1, 2017 #5

    CWatters

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    PS it's nothing to do with "screening".
     
  7. May 5, 2017 #6

    rude man

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    Nope.
    Reconsider post 2. Diligently.
     
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