Re: The conceptual change process

[William Beaty <billb@eskimo.com>]

On Tue, 17 Feb 1998, David Bowman wrote:

> I think Bill's point is taken (at least by me) here.  But I want to point
> out (even though I'm sure Bill is well aware of this) that in the usual
> analogy between a capacitor and a spring the spring's steel is *not* the
> functional analog of the capacitor's "charge".


Actually, I might disagree, depending on how the term "charge" is used. 

Do we agree that the energy of a compressed steel spring is stored in
chemical (metallic) bonds of the material?  But metallic bonds are
e-fields and patterns of charge.  In my mind, capacitors and springs are
very similar because, at the microscopic level, compressing a spring
stores energy in stretched e-fields.  (Classical view obviously, since QM
applies to metallic bonds but not so much to "charged" capacitors.")

The spring's steel is not analogous to the capacitor plates'
charge-imbalance, instead it is analogous to the capacitor plates'
substance: the electrons and protons of the metal material.  If I pull two
iron atoms away from each other in a metal crystal, I store energy in the
distorted e-fields.  If I pull an electron away from a metal capacitor
plate and deposit it on the other plate, I've stored energy in distorted
e-fields.  It's not even an analogy for a spring, since an "energized" 
capacitor IN FACT contains a gigantic ionic bond which can store energy in
the form of "stretched" e-fields.  The analogy would be perfect if the
spring was made from NaCl.  Capacitors are giant atoms, or conversely,
chemistry is simply a naturally-occurring form of nano-electronics. 
"Mechanical" effects and "electrostatic" effects become the same at the
microscopic level, and so at the macro level, compressed springs have a
deep conceptual link with capacitors.

  P.S. did everyone receive the big wad of messages I sent this morning?
  I didn't see them come back through phys-L, but then eskimo.com reported
  a dead frame relay and my incoming mail may have been vanishing during
  their repairs.

((((((((((((((((((((( ( (  (   (    (O)    )   )  ) ) )))))))))))))))))))))
William J. Beaty                                  SCIENCE HOBBYIST website
billb@eskimo.com                                  www.eskimo.com/~billb
EE/programmer/sci-exhibits          science projects, tesla, weird science
Seattle, WA   206-781-3320          freenrg-L taoshum-L vortex-L webhead-L