How is a magnetic field wave produced?

Discussion in 'General Electronics Chat' started by electronewb, May 29, 2013.

  1. electronewb

    Thread Starter Member

    Apr 24, 2012
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  2. crutschow

    Expert

    Mar 14, 2008
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    A oscillating current in a wire produces both an electric and magnetic field. These can propagate through space with the wave energy existing in the oscillating electric and magnetic fields, hence the term electromagnetic wave.
     
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  3. electronewb

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    Apr 24, 2012
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    So both waves are created at the same time? Or the magnetic field is cause by the electric field?
     
  4. nsaspook

    AAC Fanatic!

    Aug 27, 2009
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    Crutschow is correct, the electromagnetic field is a dual entity.

    http://en.wikipedia.org/wiki/Jefimenko's_equations
     
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  5. electronewb

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    So in a radio signal what is the role of the magnetic field? I assume the electric field is the carrier?
     
  6. Brownout

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    Jan 10, 2012
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    The magnetic wave is created by oscillating current. The electric wave is cause by oscillating voltage.
     
  7. nsaspook

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    They both carry the energy of the wave. Without both there can be no energy flow in the wave, it's like a circuit with a perfect insulator or a superconductor, all voltage with no current or all current with no voltage equals no power. Due to the impedance of free space the ratio of field strength is usually greater in the E field but antennas using primarily the magnetic component of an EM wave are common. Your typical AM ferrite antenna is a good example where we create a low impedance path for a radio signal causing the received magnetic field ratio to be greater.

    http://en.wikipedia.org/wiki/Loop_antenna#AM_broadcast_receiver_loop_antennas
     
    Last edited: May 31, 2013
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