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Laminated iron core inside a coil magnetic field question

  1. May 13, 2014 #1
    A laminated iron core was inserted into a coil with an AC current flowing in the coil.

    1.The current in the circuit decreased after inserting the core.

    2.Also the magnetic field was found to be stronger on the outer edge than in the center of the laminated iron core.

    How to explain the fall of the current and the differences in B on the core?

    My thoughts: I could explain 1. with the resistance of the coil increasing, thus the current would decrease. But how can you explain a resistance rise? I know the inductance L of a coil increases with a core but what if any connection is there between inductance and resistance of a coil?
    The 2nd question seems even more tricky. I read that magnetization of a core can happen gradually towards the center of a core. However the B difference was found to be stationary, it remained constant for a long time. This seems an unlikely explanation.
    Last edited: May 13, 2014
  2. jcsd
  3. May 15, 2014 #2


    User Avatar

    Staff: Mentor

    Hi wetback. Nothing to do with resistance. It's all to do with inductance (inductive impedance), and how it changes if you provide a suitable core.

    How did you sense/measure the magnetic field inside the core? What % difference, roughly, did you note in the field strength?

    This does appear to be a homework type question, so should be in the homework section.
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