A sudden memory: In the Exploratorium's collection of electrical exhibits
I saw a neat little demo of the "inertia" of the "electron stuff". There
was a massive aluminum donut a few inches across, made from 1" square
aluminum rod stock. A heavy iron laminated split-core with a coil was
clamped around one part. The split-core had the shape of two "C"s. If
the museum visitor held the halves of the split-core together and released
them, the lower half immediately fell off. If the halves were held
together and DC was passed through the coil, the halves of the iron ring
core would attract fiercly together.
And finally the inertia: if the DC circuit was suddenly disconnected, the
halves of the c-core did NOT instantly fall in two even if you pulled upon
it. Instead there was an easily-perceived delay, maybe with a .5 second
time constant. When the coil was suddenly turned off, a current of equal
amp-turns was induced in the thick aluminum ring. Because of the presence
of the closed iron pathway, the RL time constant of this circuit was
amazingly long.
And so, the "weightless silver tar" within a metal bar can be given a very
high "mass" by wrapping an iron ring around the bar. If electron-stuff is
like a substance, then nearly all of its mass/inertia property appears in
its b-field, and manipulation of its b-field can change its "mass".
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William Beaty voice:206-781-3320 bbs:206-789-0775 cserv:71241,3623
EE/Programmer/Science exhibit designer http://www.eskimo.com/~billb/
Seattle, WA 98117 billb@eskimo.com SCIENCE HOBBYIST web page