Re: Dead Electrical Guys Re: electrical units

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

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