Re: Dead Electrical Guys Re: electrical units

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: Jim Lux <jimlux-at-earthlink-dot-net> 

At 08:17 AM 2/5/2004 -0700, you wrote:
>Original poster: "Antonio Carlos M. de Queiroz" <acmq-at-compuland-dot-com.br>
>Tesla list wrote:
>
> > Original poster: Jim Lux <jimlux-at-earthlink-dot-net>
>
> > I wasn't so much wondering about the names, but how the general magnitude
> > of the unit was chosen in the first place.
>
>Looking at Maxwell's book (1873):
>
>One unit of charge is the amount of charge that when placed at two
>points separated by a distance of one unit of length produces one
>unit of force between the points. (Using 1 meter and 1 Newton, the
>result is 1 Coulomb.)
>
>One unit of current is one unit of charge flowing in one unit of time.
>(Using Coulombs and seconds, the result is in Amperes.)
>
>One unit of potential is the potential developed across a unit of
>of resistance when one unit of current passes through it.
>(Using Amperes and Ohms, the result is in Volts.)
>
>The unit of resistance is arbitrary, the Ohm. It was defined as the
>resistance that corresponds, in the old electromagnetic system of
>units (in this system u0=1, and resistance has a dimension of speed)
>as 10000000 meters/second.
>Georg Simon Ohm (1789-1854) was German. He derived "Ohms law" by 1825.
>
>The unit of capacitance is the capacitance that stores 1 unit of
>charge at 1 unit of potential. (Using Coulombs and Volts the result
>is in Farads.)
>
>The unit of inductance is the inductance that produces a potential
>drop of one unit when its current varies at one unit of current per
>unit of time. (using Volts, Amperes, and seconds, the result is in
>Henrys (Henries?).)
>
>Antonio Carlos M. de Queiroz

So the one arbitrary value is the Ohm, from which all the others are either 
nice "consistent" units (1 N, 1 meter, 1 coulomb), or derived from the ohm 
(i.e. the volt)