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Homework Help: Inserting iron core in an inductor coil

  1. Apr 22, 2014 #1


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    1. The problem statement, all variables and given/known data
    A coil is connected in series with a bulb and this combination is connected to a DC source. When an iron core is inserted in the coil, what will happen to the brightness of the bulb?

    3. The attempt at a solution

    When the iron core is inserted, the magnetic field changes. Thus the self inductance also changes. So the brightness of the bulb should change. I don't know if I am correct here.
  2. jcsd
  3. Apr 22, 2014 #2


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    While it is true that the inductance will change when the core is inserted, there is only a magnetic field when the current through the inductor changes.
    A DC source is a source that has a constant voltage.
    Therefore the current through the inductor does not change, it remains constant.
    Therefore there is no change to the brightness of the bulb.
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