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Re: Experiment - Displacement Current's Magnetic Fields
Original poster: "rheidlebaugh by way of Terry Fritz <twftesla-at-qwest-dot-net>" <rheidlebaugh-at-zialink-dot-com>
I have similar thoughts, but I'll add this thought. The lower the total
value the more the project is queled by instrament sensitivity Avoid
Hi-Frequency and go to large value capacitor. Not 6" but at least 1 meter
plates to make the test less sensitive to stray H-fields and stray
capacitance. By using low frequency you avoid the traveling wave effect
across the capacitor surface . With high current you avoid the u-amp
sensitivity problems and your test becomes immune to stray inputs.I would
suggest a UJT test circuit or a mechanical relay ac input and avoid all
harmonics of 60 Hz.
> From: "Tesla list" <tesla-at-pupman-dot-com>
> Date: Sun, 10 Mar 2002 19:43:12 -0700
> To: tesla-at-pupman-dot-com
> Subject: Re: Experiment - Displacement Current's Magnetic Fields
> Resent-From: tesla-at-pupman-dot-com
> Resent-Date: Sun, 10 Mar 2002 20:07:51 -0700
> Original poster: "Mark Fergerson by way of Terry Fritz <twftesla-at-qwest-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:
> ____________| |__________
> | ____________ 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