Re: A rotating disk PARADOX??

From: JM Albuquerque (jm.aREMOV.E_at_sapo.pt)
Date: 07/09/04 

Date: Fri, 9 Jul 2004 23:00:17 +0100

"sal" wrote:

> On Thu, 08 Jul 2004 17:20:52 +0100, JM Albuquerque wrote:
>
> > This is not an easy question I I've spend lots of time thinking. I've
> > found 3 main arguments against the theory: - The theory cannot explain
> > why rotation clockwise gives a result and rotation counter-clockwise
> > gives an opposite result.
>
> Huh? Why don't you think reversing the rotation should reverse the
> current?
>
> The B-field force is VxB, and when you reverse V, the force
> reverses. Everything else follows from that.

So the right hand rule applies with eyes closed and without a single clue.
And you claim it is conventional science, as understood by generations
of electrical engineers and physicists.
Something is missing.

> > - The theory breaks down in a superconducting disk,
> > because the generator still works if disk resistance is zero
>
> How do you know?

Because resistance changes with temperature and everybody knows that the
colder the generator is the better. What's different in the homopolar
generator ?

> I don't think it does.

Have you think of it ?

> For one thing, common superconductors expel a magnetic field...

Yes, that's why they work better.
With what magnets you think particle accelerators work ?
http://hyperphysics.phy-astr.gsu.edu/hbase/solids/scmag.html
http://hyperphysics.phy-astr.gsu.edu/hbase/solids/meis.html
Take a look of type II materials.

> > and so you
> > don't have anymore the basic cause to drive the theory (no electrical
> > resistance, no cause). - From the mechanical point of view, electricity
> > cannot have mass, so it cannot be electrons, otherwise centrifugal
> > forces will show up clearly, proportional to electron-proton mass ratio
> > and doubles if one compares clockwise versus counter-clockwise rotation.
>
> If you spin a metal disk, you put a charge on its rim, as a result of the
> centrifugal force acting on the electrons.

Has I suspected. That does it !
I never heard that centrifugal force change sense, outward to inward, when
the applied sense of rotation changes.
Remember that voltage polarity +/- changes with the sense of rotation.

> I don't know off hand if the charge is large enough to measure. Whether
> or not it is, however, the point is "electricity" does have "mass".
>
> I don't know what you mean by "doubles if one compares clockwise versus
> counter-clockwise rotation".

Easy.
Electron have mass and the centrifugal force is F = m r w^2 outward.
Since voltage polarity +/- changes with the sense of rotation, to have the
same effect you must have the same force inward and also balance the true
centrifugal force that didn't disappear. Hence doubles.

> >> Here's a picture of the disk, in the field, with the path of an
> >> electron shown as it appears in the laboratory frame:
> >>
> >> http://physicsinsights.org/images/disk_with_current_flow.png
> >
> >
> > The disk sense of rotation is wrong.
> > No big deal but it is wrong.
>
> I think it's correct.
>
> Electrons are carried around by the disk, so they must spiral in the same
> direction as the disk is rotating. (The only tangential force on them,
> aside from the B field's effect, is due to the disk's rotation.)
>
> The B field points up, the rotation is counterclockwise, so the force on
> a positive charge will be radial, directed outward.
>
> Electrons have negative charge, so the force on them will be radial,
> directed inward.
>
> So, with an upward B field, and counterclockwise rotation, electrons will
> spiral counterclockwise (with the disk's rotation) and will spiral inward
> (due to the B field force).
>
> Which part of this do you think is wrong?

Sorry. You are right.
I had the centrifugal force in mind (outward not inward).
I've study a spiral device during so many years that I cannot avoid to think
about him.

> >> Just eyeballing that, we can see what the forces must be. Here they
> >> are:
> >>
> >> http://physicsinsights.org/images/forces_on_electron.png
> >
> >
> > There is no force system equilibrium in the above image. Your
> > "resistance force" must be to the right, like PMB's paper shows.
>
> That is the fourth arrow, which I left out.

If so you have a problem when you reverse the sense of rotation.
The "resistance force from rotating disk" will be always outward (because we
don't want to have Newton rolling on the grave), the "force due to magnetic
field reverses", the horizontal force remains horizontal and the balance of
vertical forces goes down the drain.

Of course that you will say that the "resistance force from rotating disk"
also reverses sense. Newton will roll of the grave.
You cannot invoke mass to explain electricity.

> PMB's paper, on the other hand, left out any discussion of where the
> "push" on the electrons actually comes from (electrostatic field in the
> wire or resistance in the disk).
>
> The "resistance force" which I showed is actually the force which the
> electrons would feel from the disk's resistance if they were _stationary_
> in the laboratory frame. Since they're moving relative to the laboratory,
> things are more complicated.
>
> The resistance force will act very much like sliding friction between a
> block and a rotating table, and I oversimplified it in that diagram.

You can do the turns you want, but with a rotating disk and Newton mechanics
you cannot have an inward force due to rotation, never.

[ ... ]
> Right, and as I said, if you spin a metal disk, a (very!) small negative
> charge will appear on its rim.

Negative or positive, it depends on the sense of rotation.
That's where the resistance model fails.

> >> > I disagree.
> >> > The electrical resistance cannot be the cause for electricity.
> >>
> >> When the conductor is moving, it's the resistance which drags the
> >> electrons along with it, and in that sense, it is indeed providing the
> >> "work" to generate the electricity.
> >>
> >> A homopolar generator using a superconducting disk would very likely
> >> not work (but I haven't thought it through so I'm not sure).
> >
> >
> > That's a good point.
> > I guess a superconducting disk must work as well. The homopolar
> > generator cannot be a special case.
>
> Hmmm? Special in what sense? Most circuits wouldn't work if you
> suddenly replaced all their resistors with superconductors.

Yes, but circuits will work fine if you replace the wires by superconducting
wires and leave the same resistors. The disk is not the load resistor. The
disk is just a conductor whose resistance is negligible compared to the load
resistor. More or less resistance of the disk is not a problem, because the
load resistance is much higher.

[ ... ]
> Angular momentum and rotational velocity are both just pseudovectors.
> The "sense of rotation" is something impressed on them by people, who like
> right-hand coordinate systems.

Just reverse the sense of rotation of a power generator and you will see the
difference, or else look behind and shift to reverse in the high-way (no
problem since you are looking behind).

> > I'm quit sure there is no explanation for the electric and magnetic
> > field working mechanism.
> > If such explanation exists everybody will know it by now.
>
> According to a very knowledgeable EE I know, the reason you can connect a
> bonding wire to a silicon chip without making a diode which would prevent
> current from flowing, but you can also connect the same sort of wire to
> the same sort of chip in such a way that it makes a Schottky diode, is....
> "black magic".
>
> Now you know.

If you believe you know, then you are wrong.
Nobody knows, but we do have theory for everything.

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