Quote from: sm0ky2 on February 29, 2008, 01:22:52 AM
i disagree there, 

i think the disk is moving relative to the magnetic field.
i dont think this effect can occur any other way.


the charge separation on the disk is relative to both the strength of the field, and the rpm of the disk.

so, a disk spinning in free air, WOULD produce a charge - because of the earths magnetic field.
however, the RPM would have to be considerably high.... and may exceed the tensil-strength of some disks...

It is fine to disagree.  Everyone is entitled to their opinion.  I fail to see the difference of a disk spinning in front of a magnet or in the magnetic field of the earth.  Same thing.

http://www-istp.gsfc.nasa.gov/Education/wtether.html 
As I posted earlier the space shuttle was doing an experiment with a tethered satellite when the tether broke, melted by the electric current.  This experiment was to produce electric power as a homo polar generator with a vertical line acting as the disk.  The tether lit up with electrical potential so that it could easily be seen from a distance of over 100 miles.   

yes and HOW fast was that tether moving?

the difference by putting the magnet right in front of the disk is the strength of the magnetic field.
you dont need to spin the disk nearly as fast to create the same charge imbalance.

also the earth's field is set up a little different than a single-magnetic face pressed against the disk.

I think this topic is very interesting...so i'd like to add some of Tesla's notes..
To return to the principal subject; assume the conditions to be such that the eddy currents generated by rotation of the disc strengthen the field, and suppose the latter gradually removed while the disc is kept rotating at an increased rate. The current, once started, may then be sufficient to maintain itself and even increase in strength, and then we have the case of Sir William Thomson's "current accumulator". But from the above considerations it would seem that for the success of the experiment the employment of a disc not subdivided would be essential, for if there should be a radial subdivision, the eddy currents could not form and the self-exciting action would cease. If such a radially subdivided disc were used it would be necessary to connect the spokes by a conducting rim or in any proper manner so as to form a symmetrical system of closed circuits.
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the external circuit may also be arranged perfectly symmetrical to the field magnet, no reaction can occur. This, however, is true only as long as the magnets are weakly energized, for when the magnets are more or less saturated, both magnetizations at right angles seemingly interfere with each other.
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Similar dispositions may, of course, be made in a type of machine in which, instead of a disc, a cylinder is rotated. In such unipolar machines, in the manner indicated, the usual field coils and poles may be omitted and the machine may be made to consist only of a cylinder or of two discs enveloped by a metal casting.
    Instead of subdividing the disc or cylinder spirally, as indicated in Fig. 4, it is more convenient to interpose one or more turns between the disc and the contact ring on the periphery, as illustrated in Fig. 5........notes on unipolar dynamo....
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Scotty.....Tesla was a funny guy....you see he writes all about various ways ect ect....subdividing......but in the end...he shows the best model is a non-divided disc....and also a concucting belt between 2 discs to form the circuit.......
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http://patimg2.uspto.gov/.piw?Docid=00406968&homeurl=http%3A%2F%2Fpatft.uspto.gov%2Fnetacgi%2Fnph-Parser%3FSect1%3DPTO1%2526Sect2%3DHITOFF%2526d%3DPALL%2526p%3D1%2526u%3D%25252Fnetahtml%25252FPTO%25252Fsrchnum.htm%2526r%3D1%2526f%3DG%2526l%3D50%2526s1%3D0406968.PN.%2526OS%3DPN%2F0406968%2526RS%3DPN%2F0406968&PageNum=&Rtype=&SectionNum=&idkey=NONE&Input=View+first+page
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Scotty

HI Folks,

Here is a link for any US patent download in PDF file format: http://www.pat2pdf.org/ 

and copy and paste this Tesla Patent#:   406968

The link Scotty provided to this patent needs TIFF picture file viewer that members may not readily have here.

Gyula

Gearhead writes:
>http://en.wikipedia.org/wiki/Faraday_paradox
>"The magnetic field will be independent of any rotation of the magnet. In this configuration, the polarisation >is determined by the absolute rotation of the disk, that is, the rotation relative to an inertial frame. The >relative rotation of the disk and the magnet plays no role." 

This is not entirely true.  The Barnett effect shows that the angular momentum of a ferromagnetic body changes when it becomes magnetized, as the electron spin of the unpaired electron orbitals align.  Thie Barnett effect should exhibit reciprocity, although, I do not know if it has ever been demonstrated.