🚀 go-pugleaf

In article <1992Aug03.024735.9267@norfolk.vak12ed.edu>,
fculpepp@norfolk.vak12ed.edu (Fred W. Culpepper) writes:
|>John,
|>
|>	Jacob's Ladder will not operate in the normal fashion
|>when the two rods are in a horizontal plane. 

Great. I assume this means that you actually did the experiment.
This is a good fact to know.

|> The arc does
|>depend upon the rising heat of the arc.  This can be
|>demonstrated with a source of compressed air (Please! from a
|>safe distance).  If a jet of air is blown toward the arc, it
|>can be made to stand still or even go back down.  If the air
|>pressure is high enough it will even "blow-out" the arc and it
|>will reform at the base.

What this says to me is that forces from pressure differentials
due to uneven heating are more important than electromagnetic
forces on the current loop. This I can believe especially when I
look at the numbers you give below and realize that you are talking
about pressures of about 1 Atm and temperature differentials from
ambient to arcs while the magnetic field is only that due to the
relatively weak Earth's geomagnetic field. In plasma terminology, 
this would be called a "high beta" system. Beta is the ratio of 
fluid pressure to magnetic pressure.

Assuming that you have one of these critters around to play with,
let me suggest 2 additional games.

What is the difference between upright, horizontal, and inverted
arrangement of the rabbit ears? You described upright and horizontal.
Try inverted if you can turn it over without zapping yourself (or
children, heaven forbid another Disney sequal --- Honey I fried
the neighbor's child). In the inverted position gravity is again
parallel to the natural motion (along the rabbit ears) while in the
horizontal direction they are perpendicular. This can sometimes cause
very different behavior as measured by various transport parameters.

Second, if at all possible, try to put the entire apparatus into a
large volume magnetic field. It doesn't necessarily have to be
uniform, but a uniform field will be easier to calculate the 
effects (spherical cow approximation). The behavior might be
different. I'm not working the numbers here, but my guess is that
you will begin to see magnetically dominated behavior for fields
of 1-10 KGs (0.1-1 Tesla). Well maybe those fields are a bit large
to obtain easily in your garage.                        

john w. cobb
jwc@fusion.ph.utexas.edu

%
% Physics is an empiricle science
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