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Re: A NASA displacement current motor!- was Re: TC Secondary Currents - was



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

Hi All

Folk do seem to have trouble coming to terms with displacement
current.  It's just the coupling between the E field and the B field,
complimentary to Faraday's law which couples the B field back to the
E field.  Considering the overwhelming evidence for the consequent
effects of this two-way coupling, its hard to understand why it
meets such resistance. 

At one time, Maxwell's displacement current was regarded as a basic
hypothesis of EM theory, and was necessary in order for EM to account
for observed phenomena.  Nowadays, with our much deeper understanding
of EM in terms of quantum electrodynamics - the theory of charges and
photons, we no longer need the hypothesis, instead the E and B fields,
and the relationships between them - Maxwell's equations, emerge as a
consequence of the bulk behaviour of vast numbers of virtual photons
which constitute the underlying field that we measure as E and B.

We now understand that E and B are really just two apparitions of a
single field.   This is easily demonstrated by considering a charged
object floating in space.  Park next to it, and you detect only an
electric field.  Move past it at some speed, and you now see a mixture
of electric and magnetic fields.  The charged object hasn't changed,
nor has the field, its just that your relative motion has given you a
different view of it.  So E and B are not intrinsic to the field.

The connection goes much deeper, involving space and time.  For
example, with a knowledge of just electrostatics and the properties
of spacetime, you can predict the existance of magnetism and predict
its laws, and vice versa.  Quantum electrodynamics is a strange
theory that lays open before us a very odd universe underlying our
familiar reality.  Needless to say, it's been tested to death and
qualifies as the most accurate and well tested theory ever devised.
It accounts for all known EM phenomena, plus quite a few things that
EM doesn't account for.

It's worth remembering when we're messing around with our coils and
swapping ideas, that physics has moved on a long way in front of us,
and most of our silly debates revolve around personal and popular
misunderstandings.  We still seem to persist in raking through the
remnants of 19th century arguments that have long since been cleared
up.

When it comes to Tesla coils, we never experience the magnetic
consequences of displacement currents - the frequencies are far too
low.  Instead, we see charge piling up on electrode A and an equal
amount draining away from another electrode B.  We have a conduction
current shifting the charge from B to A, and sometimes it is
convenient to speak as if the charge returned from A back to B as a
current, whereas in reality it is just piling up at A.
--
Paul Nicholson
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