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How does wireless power transfer produce magnetic flux?

  1. Jul 19, 2012 #1
    From what I learned, for an electric current to be induced in a wire, there must be a magnetic flux. On youtube, there are lots of videos showing wireless power transfer to a lightbulb or LED. However, the light is constant. How is the magnetic flux changing in such a setup?
  2. jcsd
  3. Jul 19, 2012 #2


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    The flux must be changing in time (alternating) for any sustained induction to take place.
    When you turn on the AC mains supply to a light bulb, the light appears constant whereas it is actually flickering (to some extent) at the rate of the AC. Power is transferred 'wirelessly' even for mains AC, whenever transformers are used. There is no actual 'wire' connection between primary and secondary windings. The transfer of power is due to the alternation of the magnetic flux. This is the same for wireless links which operate at higher frequencies and the perception of any flickering is much reduced by the circuitry and also by the response our eyes' photo-receptors. For wireless power transfer over a long distance, the electric field variation also counts.
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