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Re: AC electricity

At 02:19 PM 1/17/01 -0700, Larry Woolf wrote:
I personally like the analogy of the pin ball machine. The pins represent
the fixed ions in the lattice. The balls represent the free electrons.
When the machine is tipped one way (positive voltage across the resistor),
the balls (electrons) flow downhill and bump into the pins (dissipating
energy - heat).

One must be careful with such analogies. In a pinball machine, there can
be local accumulations of balls here and there. In the regime where
Kirchhoff's laws apply, this does not happen with electricity.

One could try to envision an incompressible fluid of pinballs.... but then
the fluid analogy has problems, too! When you open-circuit an ordinary
fluid-filled pipe, the fluid spills out, but when you open-circuit an
ordinary wire, the electrons don't spill out.

Maybe we could envision really tiny pinballs that mutually repel each other
with a 1/r potentials so they don't readily accumulate, yet are attracted
to the lattice they're in so they don't spill out, and ...... :-)