Woops, made a mistake, not enough sleep today, purely an AC effect, NOT
DC as this might imply;
> Now doesn't that evoke an interesting question? Aluminum will repel
> from a high density magnetic discharge REGARDLESS OF POLARITY, but
> ONLY ONE POLE AT A TIME...either North or South.
I meant as AC and the way I wrote it sounds like DC...it is the
alternation between poles that produces the remanence lag and thus
repulsion.
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Here is a picture of the science museum type demo of repulsion by AC;
http://www-physics.ucsd.edu/was-sdphul/labs/demos/electrod/AC-COIL.html
A large electromagnet, with a movable iron core, is energized with AC
power. An aluminum ring, placed over the extended core, is propelled
upwards by about two feet when the coil is suddenly energized. The ring
will also be levitated around the core if the power is left on. WARNING
Rings left on the energized core will heat considerably!
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http://www.astro.virginia.edu/~eww6n/physics/HysteresisEffect.html
Hysteresis Effect
The magnetization of Ferromagnetic substances due to a varying magnetic
field lags behind the field. This effect is called hysteresis, and the
term is used to describe any system in whose response depends not
only on its current state, but also upon its past history. The loss of
energy per magnetization cycle per volume is given by Steinmetz's
Equation.
=====================
http://www.lassp.cornell.edu/sethna/hysteresis/WhatIsHysteresis.html
Hysteresis represent the history dependence of physical systems. If you
push on something, it will yield: when you release, does it spring back
completely? If it doesn't, it is exhibiting hysteresis, in some broad
sense. The term is most commonly applied, as Webster implies, to
magnetic materials: as the external field with the signal from the
microphone is turned off, the little magnetic domains in the tape don't
return to their original configuration (by design, otherwise your record
of the music would disappear!) Hysteresis happens in lots of other
systems: if you place a large force on your fork while cutting a tough
piece of meat, it doesn't always return to its original shape: the shape
of the fork depends on its history.
Many hysteretic systems make screeching noises as they respond to their
external load (hence, the natural connection with hysteria).
======================
http://www.phy.mtu.edu/LECDEMO/websit/j1-26.htm
DESCRIPTION: A group of aluminum pie pans is placed on top of the Van de
Graaff dome and the Van de Graaff is turned on. The pie pans are pushed
off the top of the dome one at a time by the electrostatic repulsion.
Use this as a way to argue that electrostatic forces might be stronger
than gravitational forces.
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-- Jerry Wayne Decker / jdecker@keelynet.com http://keelynet.com / "From an Art to a Science" Voice : (214) 324-8741 / FAX : (214) 324-3501 KeelyNet - PO BOX 870716 - Mesquite - Republic of Texas - 75187