Re: TC Secondary Currents - was ( Experimental Help - Terry?)

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Jim Lux by way of Terry Fritz <twftesla-at-qwest-dot-net>" <jimlux-at-earthlink-dot-net>

Oddly, some 25 years ago, I attempted to do just this measurement in high
school after I found out about Maxwell's equations... I had a capacitor
which was charged by a Wimshurst machine, with a magnetic probe in the field
(multiple iron wires forming a core, and a sense coil on the core, feeding
an amplifier and oscilloscope with a camera)  Never got any unequivocal
results, and I was just looking for some sort of qualitative result... (move
the probe around in various orientations and positions, and the detected B
field should change in some nice repeatable fashion...)

The real problem is that c^2 proportionality constant.  It takes a HUGE
change in electric field going very fast (in my case, a spark gap discharged
the cap) to produce a very small magnetic field, which is tough to detect in
the presence of all that changing E field.


----- Original Message -----
From: "Tesla list" <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Sunday, March 03, 2002 6:27 PM
Subject: Re: TC Secondary Currents - was ( Experimental Help - Terry?)


> Original poster: "Antonio Carlos M. de Queiroz by way of Terry Fritz
<twftesla-at-qwest-dot-net>" <acmq-at-compuland-dot-com.br>
>
> Tesla list wrote:
>
> > Can you give an experimental reference to this mysterious magnetic field
> around
> > this "displacement current"?  Can we measure it magnetically?  Could a
small
> > flat plate capacitor placed in the center of a Pearson current
transformer
> > measure this current?  It can sure measure the current in the leads up
to the
> > capacitor.
>
> The electric field between the plates of the capacitor is changing while
> it is being charged, and a changing electric field produces a changing
> magnetic field.
> I didn't try this, but I imagine that if you make a small coil probe,
> connected to an oscilloscope (or simply an AC meter), and place it
> between the plates (axis parallel to the plates) of a capacitor that
> is being charged of discharged (or simply with an AC voltage applied
> on it) you will see the magnetic field caused by the displacement
> current. A current transformer would serve too (magnetic loop parallel
> to the plates).
> A problem is that it can be difficult to separate the magnetic field
> generated by the displacement current  from the field generated by the
> wires going to the capacitor plates and by currents in the plates
> themselves. But you can short-circuit the capacitor, while keeping
> the same current through it (connecting an AC current source to the
> capacitor) and see if something changes.
>
> Antonio Carlos M. de Queiroz
>
>
>