Re: Flat conductors

[Brian Whatcott <inet@INTELLISYS.NET>]

At 04:48 PM 3/8/02, you wrote:
> Brian Whatcott wrote:
>
> > I WAS equating the phrase "electric permeability" to electrical
> > conductivity (sigma=1/rho).
>
> 1) I am confused because I would not know how to interpret
> a sentence such as "the permeability of material X is equal
> to its electric conductivity." These are two different quantities.
....
> Ludwik Kowalski

This note carries a certain resemblance to the plaintive concerns
of readers of physical texts who find a single letter may represent
various different physical measures on different pages, without
any warning.
In this case, there is a word used in several technical senses, 'permeability'.
In sedimentary studies it may be a measure of the readiness of ground
water to percolate to the water table, in matters of bulk resistivity it may
represent the facility with which charge carriers penetrate the medium,
in matters of magnetic intensity, it may measure the degree of intensification
 of a magnetic field by a particular material.
Writers who wish to be humane, may prefix their usage with the area of
interest, as I did: electric-, magnetic-, gas-, water -permeability.

Still, to reiterate the point: magnetic flux can wonder off the edge of (say)
a sheet of iron -
but electric current does not wonder off the edge of the resistance paper.


Brian Whatcott
  Altus OK                      Eureka!