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Question related to electromagnetic theory

  1. Sep 3, 2009 #1
    A circuit contains an iron cored inductor, a switch and a DC source arranged in series. The switch is closed and after an interval reopened. Explain why a spark jumps across the switch contacts.
    I guess it's related to self induction and back emf but am unable to understand how a spark can be produced in such a case...
  2. jcsd
  3. Sep 7, 2009 #2


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    on the right track, to produce an electrical arc, you first need quite a large voltage...

    thinking about whats going on, before opening the switch you have a steady flow of current through the inductor, which produces a magnetic field

    when you open the switch you immediately intererupt the current & so the magnetic field...

    can you find any equations to help explain what is going on...
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