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Output of a transformer plugged into a DC voltage source by mistake?

  1. Mar 10, 2009 #1
    1. The problem statement, all variables and given/known data
    What would be the output of a transformer plugged into a DC voltage source by mistake?

    2. Relevant equations

    3. The attempt at a solution
    Judging from the phrasing of the question, I am assuming that a transformer should not be plugged into a DC voltage source but rather AC voltage. I do not know anything about transformers, but I would think that doing this by mistake would either cause the transformer to short or nothing at all would happen. Is this correct?
  2. jcsd
  3. Mar 10, 2009 #2


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    Homework Helper

    Re: transformer

    Transformers work on these two principles:
    - a current causes a magnetic field around it
    - a changing magnetic field causes an electric field around it, which tends to create an electric current in a conductor

    The transformer works as long as the primary current is changing, which it will be for a very short time until the DC current stabilizes. So you will get some output for a millisecond or two, then nothing.

    Your thought that their could be a short circuit makes sense. The DC will not notice the reactance of the primary coil, so the current may well be too large.
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