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Induction Coils and/or Hertz Experiment

  1. May 14, 2007 #1
    Hi everyone,

    Just a quick question that was bugging me...

    If i was asked to draw the voltage output vs time of an induction coil...would it be absolute value sine curve??

    Secondly i absolutely dont understand how in Hertz experiment, what the sparks jumping across have anything to do with oscillating electric field. If the source of the voltage is from an induction coil...then on electrode is always positive and the other always negative. The only change is that they vary from high potential difference to zero continuously (assuming my question 1 hypothesis is right).

    So there is an electric field, then there isnt, then there is, then there isnt and so on...but whenever there is...its always in the same direction. So how is the EM wave produced??

    Really welcome and appreciate anybody's help....
  2. jcsd
  3. May 15, 2007 #2
    The important point is not the oscillating field, it is the changing field.
    Changing rapidly in a "spark" is like changing rapidly in a high frequency oscillating field, the difference is that oscillating implies frequent repetition of this changing field.

    For the exact mathematical description, try to look for Fourier transform.
    This will show you how any signal, even limited in time, can be seen as a superposition of oscillating signals.
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