Re: Magnetic field and relative motion

From: V.K.Tamhane (vktamhane12_at_rediffmail.com)
Date: 06/19/04 

Date: 19 Jun 2004 06:30:13 -0700

"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.
 
> > 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.

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