Dual CPU nodes?
math at velocet.ca
Tue Oct 22 12:55:44 PDT 2002
On Tue, Oct 22, 2002 at 12:29:31PM -0400, Robert G. Brown's all...
> which alas is not very knowable without knowing dI/dt. If the line
> current dropped to zero VERY quickly this could be quite large, but
> usually a similar induced voltage causes e.g. arcing that keeps it from
> being that large. If we assume that the current drop occurs in a
> microsecond, V_b could be order 0.1 volts. Assuming that the resistance
> of the bracelet is very small, even this voltage could create a single
> pulse of current. Making it a very generous I_b = 1000 amps (assuming
> that the resistance of the bracelet is around 0.001 ohms) the peak force
> of attraction should have been strictly less than (and WAY less than,
> since forces on the half of the bracelet nearest the wire should have
> been nearly cancelled by forces on the far half of the bracelet)
> B(r)*I*(0.1) or less than 0.0001 Newton's (lasting a tiny fraction of a
> second) which should hardly have made his hand jump up. Even if there
> were a single unshielded power bus carrying several hundred amps PLUS
> the inductive current peak order a kiloamp, the two meters and extremely
> short duration of the attractive force should have imparted almost no
> momentum to the bracelet.
> Among our demos, we have a "magnetic cannon" which consists of a coil
> with maybe a thousand turns wrapped around an iron core (which confines
> and significantly enhances the resulting magnetic field). A conducting
> ring some 3 cm across is placed over the iron core and electric line
> current is switched on with an ordinary switch, where I'm guessing that
> the line current is order of 1 A peak. The ring jumps off quite
> satisfactorily. However, it doesn't shoot as high as the ceiling (it
> goes up maybe half a meter) and can easily be held down with a hand,
> although it gets very hot very quickly if one does this as it acts like
> a transformer coil.
> So I'm just surprised that a single line, with field unenhanced by iron,
> could create so great an impulse in a similar conducting ring roughly
> two meters away. I'd love to understand how it happened.
Me too, this is why I am asking - what other kinds of semi-standard wiring
and transformer configurations found in a typical lab (thats not a power
electronics research lab, nor has megawatt lasers in it :) that could
cause this? can you think of any configuration that would result in this?
> Robert G. Brown http://www.phy.duke.edu/~rgb/
> Duke University Dept. of Physics, Box 90305
> Durham, N.C. 27708-0305
> Phone: 1-919-660-2567 Fax: 919-660-2525 email:rgb at phy.duke.edu
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Ken Chase, math at velocet.ca * Velocet Communications Inc. * Toronto, CANADA
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