Re: Magnetic field and relative motion

From: Harry (harald.vanlintel_at_epfl.ch)
Date: 06/20/04 

Date: 20 Jun 2004 06:22:04 -0700

vktamhane12@rediffmail.com (V.K.Tamhane) wrote in message news:<9d62a326.0406190530.3ad97bc5@posting.google.com>...
> "Harry" <harald.vanlintel@epfl.ch> wrote in message news:<40d29fe0$1@epflnews.epfl.ch>...
> > "V.K.Tamhane" <vktamhane12@rediffmail.com> wrote in message
> > news:9d62a326.0406150313.241a71b0@posting.google.com...
> >
> > SNIP
>
> Don't snip the important portion. Tell me if the diodes are
> introduced, will there ever be charges collected at the brushes of the
> stationary circuit? ( that is when only the disc is rotating). If not,
> it means the observation made from the disc is apparent.

Sorry but no time to study new cases and too long ago that I studied
this that's why I snipped it, only want to help you with info. The
basic conclusion is that when coil is moving relative to magnet than
power can be generated.
Nothing to do with the lorentz transformations, despite the confusion
of Einstein to think that it does.

> > > Let me refer to the actual experiment conducted.
> > > (J.W.Then,"Experimental study of the motional electromotive force",
> > > American journal of physics,30,411,1962).
> > > Refer fig.2. Disc shaped ceramic magnet M was placed in
> > > the brass cup F, co-axially. Magnetic flux was normal to the
> > > cylindrical side of the cup and parallel to the lead wire DE. It was
> > > observed that,
> > > 1. When cup alone was rotated, emf was produced.
> > > 2. When magnet alone was rotated there was no emf.
> > > 3. When the cup and the magnet were rotated together, emf was
> > > produced.
> >
> > WHERE was it produced? In a co-moving meter? Not so if I understood well!
>
> At the points A and C.
>
> > > Note that in 2 there is a relative motion and in 3 relative motion is
> > > zero. Placing contact E at various positions of the disc AB, emf
> > > remained unaltered, proving no emf was generated in the lead wires. (
> > > If you are still in doubt then you can simply extend the length of the
> > > cup, so that the stationary circuit is in the extremely weak field.)
>
> > > This expt. proves that relative motion plays no part.
> >
> > I don't think so - Jorge Guala-Valverde et al, American Journal of Physics
> > 70, oct.2002 p. 1052:
> > "The homopolar motor: a true relativistic engine".
> > "Relativistic" was imposed on him by the referees, but he himself does not
> > have the opinion that relativity has anything to do with it. He actually
> > meant relational, that is, working due to relative motion: "The unipolar
> > motor: A genuine relational engine" - Apeiron 4, oct.2001.
> >
> > Harald
>
> Unfortunately I will not be able to go through the above mentioned
> experiment immediately. Then also draws conclusions which are funny
> and I suspect those are the referee's. The guidelines of the Journal
> state that they do not accept anything that goes against the
> established theories. Anyway the experiment disproves relative motion.

That's why I gave the precision about how to interpret it! It's a pity
to realise that the referee proces can actually mess things up...
Anyway, that experiment proved that only motion between the magnet and
the coil matters. And as it's the last one it's likely the most
authorative, as it took into account and explained all(?) the former
that concluded "Yes- No- Yes- No" !

Harald

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