Re: Non-conservative forces in a liquid dielectric

[Pentcho Valev <pvalev@BAS.BG>]

Ludwik Kowalski wrote:

> Yes, gedanken experiments are useful. The nylon springs
> were added to follow the description: "We slowly draw
> them [plates] together (step 1) and so gain some work."
> Very narrow rigid wedges (near plate corners) would be
> a better visualization for the idealized setup then the rods
> or springs. Work against electrical attraction is done by
> an agent when frictionless wedges are pushed toward
> the inside and work is done on the agent they are
> allowed to slide out.
>
> I know that I am addressing only a small detail and
> not thermodynamics of the engine. Is the reasoning
> presented by Pentcho acceptable?
> Ludwik Kowalski

Incidentally I found the message from the colleague from UCSD informing me
about his experiment in which two vertical capacitor plates are partially
immersed in a pool of water. Here it is:

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

Pentcho,

I had a factor of 4 pi wrong in my calculation of the field.
As a consequence, the effect is readily observable.
A colleague who is an experimental physicist put together a  capacitor
made of 1 in square aluminum plates spaced 1.5 mm apart.  Water rose
about halfway up the plates at this separation due to capillary action.
When a potential of 500 V was applied across the capacitor (E = 3300 V/cm)
the water rose by about .4cm -- quite visible.

We're going to cut a slot in one of the plates to make the rise easier
to see, so I'll be able to report to you on whether we get a perpetual
motion machine.  I'm betting we don't.

(Later)
Unfortunately, my colleague cut a fairly wide slot in BOTH plates.  The
result is that the water rises on both sides of the slot, but not as much
in the slot.  Still, NO tendency for the water to fall out of the capacitor
into the slot, creating a waterfall.

I'm hoping to convince him to make another with only one plate slotted with
a narrower slot.

In any case, this is a real and observable effect, and shows no signs of
producing perpetual motion or a violation of the second law -- no surprise to

me, and I suspect not to you either.

End of UCSD colleague's message------------------------------

I tried to persuade him not to cut slots but, rather, to punch a small hole
in one of the plates (in accordance with our initial plan) and see if water
would leak through the hole. He has not replied. Again, I would like to say
that what is valuable is not the violation or lack of violation of the second
law - rather, the establishment of a testing method is precious. People
prefer to believe rather than test and ruin the life of anyone who is against
believing in science. But old soldiers never give up. Aut inveniam viam aut
faciam (I shall either find a way or make one).

Pentcho