[BC] Aluminum and magnetic/electric currents

[Lamar Owen]

On Saturday 18 February 2006 18:38, WFIFeng at aol.com wrote:
> In a message dated 02/18/2006 11:34:05 AM Eastern Standard Time,
> lowen at pari.edu writes:
> > Found my reference: "Direct Current Machinery" Hempstead S Bull, John
> > Wiley and Sons, 5th printing, 1947.  Page 253, subject 'Homopolar
> > Generator'. Google for "Faraday Homopolar Generator" for more
> > information.

> All I'm finding on Google (the first 20 or so entries) all seem to be
> either "free" sites like geocities or conspiracy theory or "free energy"
> gobbledygoop. Can you give me a link to something reputable & trustworthy?
> :)

:-)

Indeed.  See the wikipedia entry for "homopolar generator".  Be sure to read 
http://www.physics.umd.edu/lecdem/outreach/QOTW/arch11/q218unipolar.pdf while 
you're at it.  I would assume that the physics department of the University 
of Maryland would be reputable enough.  Or the physics department at the U of 
Texas (http://farside.ph.utexas.edu/teaching/plasma/lectures/node70.html).  
Or perhaps Texas A&M, which has a project using a HPG for welding 
(http://otrc.tamu.edu/Pages/B5275.html).  Also see 
http://amasci.com/freenrg/n-mach.html where there are good references cited.

Don Lancaster did a couple of musings on tinaja.com about the HPG. (one is at 
http://www.tinaja.com/glib/muse117.pdf ).  Also see 
http://www.tinaja.com/glib/bashpseu.pdf where he bashes pseudoscience.

> As for my original comment, I cannot see how the tiny magnetic field of the
> Earth could possibly provide enough eddy currents to produce sufficient
> drag to make that spinning disk even slightly useful as an excercycle load.

Most literature only deals with the type with closely located magnets.  
However, the Earth's magnetic field is anything but weak, and could produce 
useful current, assuming you could get enough efficiency at the contacts.

Spin the bare disk in the Earth's magnetic field quickly enough, and you will 
get a measurable, if tiny, voltage.  You will need extremely small resistance 
connections.  And, as you load the circuit down, you will get drag.  After 
all, there's no free lunch there, just an application of the Lorentz force.

Again, the homopolar generator does not produce 'free energy' but is a simple 
DC generator, although a poorly understood one.  All you need is a magnetic 
field and the rotating disk.  Complete the radial circuit (one pole on the 
periphery of the disk, and one pole at or near its axis), turn the disk, and 
the Lorentz force guarantees you will get direct (and pure direct) current.

Homopolar generators have their uses; extremely high current output is one of 
them.

Oh, by the way: in the classical Faraday disk experiment, as performed by 
Michael Faraday, the magnet is rotating along with the conductive disk.  And 
electricity is generated.  The wikipedia article contains the links to the 
Faraday paradox and the Lorentz force articles.
-- 
Lamar Owen
Director of Information Technology
Pisgah Astronomical Research Institute
1 PARI Drive
Rosman, NC  28772
(828)862-5554
www.pari.edu