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Radio wave

  1. Mar 28, 2005 #1

    ppt

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    Hertz produce radio wave when he made an electric spark.
    Why is that spark neccessary?
     
  2. jcsd
  3. Mar 28, 2005 #2

    HallsofIvy

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    It isn't "necessary"-it was just convenient with the equipment he had. what he needed to do was produce a strong electro-magnetic wave. The spark was just a "side effect".
     
  4. Mar 28, 2005 #3

    ppt

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    I understand spark was just a "side effect".
    I need to make clear one question first.
    Is there a electromagnetic field already(in the setup)?
    If yes,
    Then why can and the process of 'making a spark' produce a strong electro-magnetic wave?
     
  5. Mar 28, 2005 #4

    SpaceTiger

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    The spark itself isn't what produces the wave, it's the oscillating current flow through the LRC circuit. The spark gap acts as a sort of cork stop to the circuit, allowing the capacitor to build up until the potential difference across the spark gap is high enough to form a spark. Once it does this, the LRC circuit is completed and the capacitor is free to discharge, dissipating energy in the form of radio waves in the process.
     
    Last edited: Mar 28, 2005
  6. Mar 28, 2005 #5
    re

    Also, the high voltage spark is a pulse with generates alot of harmonics. Hertz devised a resonator which he could tune into one of these harmonics and attenuate the rest which resulted in a more cleaner electromagnetic wave.
     
  7. Mar 28, 2005 #6

    ppt

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    Why can the oscillating current discharge energy?
    Why is the energy in the form of radio waves?
     
  8. Mar 28, 2005 #7

    SpaceTiger

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    Because accelerated charges radiate (in the classical theory). I won't get into the whole mess about consistency with the equivalence principle. The type of radiation (in this case radio) depends upon the frequency of oscillation.
     
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