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Charged inductor with no discharge path?

  1. Nov 18, 2008 #1


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    Suppose I have a simple DC circuit. If I wrap the wire around a piece of iron, I create an inductor. Having a steady flow of current creates a steady magnetic field around the piece of iron. If I remove the power supply and put a wire in its place, the magnetic field will collapse and send a current back in the opposite direction of the current which created the field.

    What happens if I don't have a nice discharge path? What if I charged the inductor then cut the wire? The field still collapses, but where does my current/voltage go?
  2. jcsd
  3. Nov 19, 2008 #2


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    For DC current, the inductor will have a current, but only a small voltage, due to its resistance, across it. When you cut the wires, a large back EMF will be applied as the magnetic field collapses. This could institute a spark whose current will end the voltage due to the EMF. This is what you notice sometimes when you remove a plug.
    If there is no spark, the EMF will first cause a current pulse in the inductor that will charge the ends, followed by a back current pulse that neutralizes the inductor.
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