Re: Experiment - Displacement Current's Magnetic Fields

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

Original poster: "Mark Fergerson by way of Terry Fritz <twftesla-at-qwest-dot-net>" <mfergerson1-at-cox-dot-net>

Tesla list wrote:
> 
> Original poster: "Paul Nicholson by way of Terry Fritz
<twftesla-at-qwest-dot-net>" <paul-at-abelian.demon.co.uk>

  Hi Paul, Terry, all:

  I can follow about half of the below, and I have a comment (the
usefulness of which depends on whether I really understood the
bits I think I did). ;>).

  This reminds me of the flaps that continue over Homopolar
machines; when somebody gets excited about them, it's usually
because they forgot about the part of the magnetic field
_outside_ the disc.

  It's relatively easy to shape magnetic fields with
appropriately shaped pieces of hi-mu material, but electrical
fields are trickier. I wonder if it would make things "simpler"
to electrostatically shield _all_ the setup (with the exception
of the space between the plates) so that the only time-varying
E-field affecting the search coil is that between the plates.
Yes, I realize that means battery power and some tricky cabling
to the plates, and taking into consideration the added
capacitance and more strongly localized fringing fields, but
eliminating the contribution of the leads to the cap might
clarify things a bit.

   ASCII (fixed-font) attempt follows:

               ___Shield___
  ____________|            |__________
  | ____________ Supply_____________  |
  | | ________              ______  | |
  | | |       |___      ___|      | | |  
\_| | |_          Shield        \_| | |_
        \                               \

\_     _                        \_     _    
  | | | \      | |  __  | |       | | | \
  | | |________| | |__| | |_______| | |
  | |____________|      |___________| |
  |____________  |  __  | ____________|
               | | |__| | |
               | |   |  | |
                     |
 
 Mark L. Fergerson

> Hi Terry,
> 
> > ...I am looking for are terribly obvious flaws
> 
> Look up the generalised Ampere's circuital law, aka the Maxwell-Ampere
> law.  That's the one that JCM invented by hypothesising the dD/dt term
> as a source for H.  The one you're trying to test.  An hours thought
> will save a weeks work.
> 
> Now read up on why he did that.  Would Ampere's law make any sense
> without the dD/dt term?  No, because it would give two different
> values for the voltage induced in your coil.  One value if you
> integrate Curl H over a surface which cuts a feedwire to your cap,
> another value if you integrate over a surface which goes through the
> cap's gap.  Thus Ampere's law would not be self consistent.
> 
> Yet Ampere's law works (it is an empirical law), and the search coil
> will give a reading consistent with both Curl H = J  *and*
> Curl H = dD/dt.  Whatever voltage appears on your search coil, you
> will not be able to tell whether it came from the J due to the wires
> leading to the cap, or from the dD/dt in the gap.  The two sources
> will give exactly the same value.
> 
> Your experiment will fail, and the dD/dt was added to Ampere's law in
> order to explain this failure.
> 
> To test dD/dt, you must look for a property of the field which
> vanishes altogether if Curl H = J + dD/dt were not a correct
> description of nature.
> --
> Paul Nicholson
> --