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Re: Displacement Current Revisited


  Richard W. -

  I understand the near field to be due to the RF currents that are flowing
in the secondary coil. According to Faraday an osillating current creates a
magnetic field around the conductor. I believe this field could be dectected
by a compass if the it is strong enough and if the sine wave is
unsymmetrical as Tesla indicated. This current is the same RF current that
produces the electromagnetic field radiating from the coil. It is also the
same current that charges the toroid.

  Do I understand correctly that you performed the compass test?

  If this test works I agree with you that it would give the polarity
regarding the offset of the wave.

  John Couture

----------------------------

At 10:45 PM 3/21/99 -0700, you wrote:
>Original Poster: rwall-at-ix-dot-netcom-dot-com 
>
>On 03/20/99 14:52:22 you wrote:
>
>>  Coilers are apparently not familiar with the induction field around the
>>Tesla coil. If I understand this field correctly a coiler should be able to
>>detect the field with a compass placed near a TC while it is energized. The
>>compass is not sensitive to the EM field but should deflect because of the
>>magnetic effect of the induction field. The compass would have to be
>>properly aligned and very close to the center of the secondary winding. Has
>>anyone tried this test? Reinhart's lamp could be used but this is also
>>sensitive to the EM field.
>>
>>  John Couture
>
>3/20/99
>
>John,
>
>I suspect that your "near field" is just composed of the concentric magnetic 
>"fields" of the DC current flowing in the TC as opposed to the EM field.  If 
>a wire with a few milliamps DC flowing through it is approached with a cheap
>compass the concentric magnetic fields are readily appearant.  Turn your TC 
>horizontally and approach the side of the coil with a compass on the end of 
>a long insulated pole.  The compass should align itself with the longitudnal
>axis of the coil confirming that it's the concentric magnetic fields of the 
>DC current in the TC.  As an aside, the electric "fields" of the DC current 
>should radiate radially at right angles to the longitudnal axis of the TC.
>
>BTW, the compass should be an easy way to establish the overall polarity of 
>DC current in a TC.
>
>R. Wall
>
>