John Larkin wrote:
On Sat, 28 Apr 2007 17:38:04 GMT, Phil Hobbs
wrote:

Michael A. Terrell wrote:
cledus wrote:
SuperM wrote:
Same as posted a few years ago.

I had a prof that referred to it as "Ohm's opinion" :-)

Did you get your money back?


It's sort of interesting that the linearity of resistance is primarily a
material property, whereas the linearity of reactance is primarily due
to the linearity of Maxwell's equations (ferromagnets apart).



Which means that resistance isn't truly linear, whereas reactance can
be. So Maxwell made laws, but Ohm didn't.

Aside from all the temperature and Hall and voltage coefficient stuff,
does pure carrier density modulate conductivity in metallic
conductors? You know, some vaguely superconductor/phonon
charge-interaction type effects? The shot noise thing implies charge
interaction.

John


Shot noise implies *no* interaction. To derive the shot noise formula,
you start by assuming that the electrons arrive in a Poisson
process--that their arrival times are uncorrelated. Most kinds of
interaction between electrons (e.g. emitter degeneration in a BJT, or
the Pauli principle in metals) tend to reduce the noise. An exception
would be avalanche multiplication.

Conductivity in metals depends mostly on scattering from and the band
structure of the metal, iiuc.

Cheers,

Phil Hobbs