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Conductor in a magnetic field

  1. Oct 25, 2009 #1
    There is this problem of a conducting rod being in a uniform magnetic field. When the rod is being moved, some answers that there will not be an induced emf as there is no change in magnetic flux linkage but some answer that there is.

    Anyone can clarify?

    Thanks.
     
  2. jcsd
  3. Oct 26, 2009 #2

    rl.bhat

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    When a rod moves in a uniform magnetic field, the charged particles in the rod experience a magnetic force F = qvBsinθ. Due to this the charged particles start moving towards one end of the rod. That causes an electric field in side the rod, which pushes the electrons in the opposite direction with a force Eq. In the equilibrium condition qE = Bqv Or E = vB. If the length of the rod is L, the emf V = E*L = vBL. So there is an induced emf in the rod.
     
  4. Oct 26, 2009 #3
    What if the conductor is immersed in the magnetic field? Is there a difference?
     
  5. Oct 26, 2009 #4

    rl.bhat

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    You are moving the rod in the uniform magnetic field. What do mean by immersing the conductor in magnetic field?
     
  6. Nov 4, 2009 #5
    I came across some question that states that if a conductor is totally immersed in a magnetic field, it should induce no emf since flux=NBA is always a constant. Is this true?
     
  7. Nov 4, 2009 #6

    rl.bhat

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    If it is a coil of conductor, it is true. But not for a rod.
     
  8. Nov 4, 2009 #7
    Oh! So ok....But for a rod, magnetic flux linkage is also NBA (N=1) right? Whats the difference?
     
  9. Nov 4, 2009 #8

    rl.bhat

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    In the case of the rod, when it moves Flux linkge is B*L*dx. The rate of change of flux is B*L*dx/dt or BLV.
     
  10. Nov 5, 2009 #9
    Ok, ok. So just to clarify, a conductor coil moving in a uniform magnetic field will not experience a emf since there is no change in magnetic flux linkage NBA. But for a rod, there will be an emf experienced since E=Blv and since there is v, there is emf?

    Thanks.
     
  11. Nov 5, 2009 #10

    rl.bhat

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    Yes.
     
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