At 23:12 03/12/99 -0500, Wagner Lipnharski wrote:
>I don't want to be a pest in your life, 
...
>you would understand if I correct you in few things, 

i had to repeat the above :)

> milli (m) 0.001
> centi (c) 100
> kilo  (k) 1,000

as a matter of fact, centi is 0.01 (not 100) as in cm (centimeter):
100cm=1m, but i'm not sure whether centi is actually part of the SI. "cm"
is probably the only really common use for "c".

> Ohms,      or R  Resistance
> Farads,    or F  Capacitance
> Henris,    or H  Inductance
> Volts,     or V     
> Current,   or I, or Ampere(s)
> Impedance, or Z
> Hertz,     or Hz

here the common abbreviations for the different -- how's that called? here
i am right at the edge of my language skills -- you-know-what-i-mean :) and
their units got mixed up (what exactly i mean will be clearer from the
slightly modified list):

capacitance (C) in Farad (F); common pF, nF, �F (uF), mF
inductance (L) in Henry (H); common �H (uH), mH
voltage (V) in Volt (V), common mV, V, kV
current (I) in Amp�re (A); common pA, nA, �A (uA), mA, A
resistance (R) in Ohm (greek Omega; often R, because Omega is rare in fonts
and on keyboards); common mOhm, Ohm, kOhm, MOhm
impedance (Z) in Ohm, too
power (P) in Watt (W); common �W (uW), mW, W, kW, MW, GW, TW
frequency (f) in Hertz (Hz = 1/s); common Hz, kHz, MHz, GHz

here one starts to see the beauty of the SI: =all= units  are
multiplications/divisions of the 7 base units meter [m], second [s],
kilogram [kg], Amp�re [A], Kelvin [K], mol (how's that in english?),
candela [cd]. 

for example (units in brackets): 
time (t) is   [s]
length (l) is   [m]
speed (v) is l/t   [m/s]
acceleration (a) is v/t   [m/s^2]
mass (m) is   [kg]
force (F) is m*a   [kg*m/s^2 = N (Newton)]
work (W) is F*l   [kg*m^2/s^2 = Nm (Newton-meter)= J (Joules) = Ws
(Watt-second)]
power (P) is W/t   [kg*m^2/s^3 = Nm/s = W (Watt)]
current (I) is   [A]
voltage (v) is P/I   [kg*m^2/(s^3*A) = V (Volt)]
resistance is v/I   [kg*m^2/(s^3*A^2) = Ohm]
capacitance is I*t/v   [s^4*A^2/(kg*m^2) = As/V = F (Farad)]

... and so on. i think this is pretty nice, especially since you can get to
one unit from different directions (like from mechanical relations and from
electrical relations), and it always works out right -- and with the units
getting "transparent," you see that all of them actually are related. you
would think "how's pounds and gallons related to Ohm?" -- but they actually
are. resistance relates to voltage and current, these relate to power,
which relates to work, which relates to length and force, which relate to
volume (gallons) and mass (pound), respectively. only that gallon and pound
don't give Ohm.

basically this is why i like the SI (also called the "metric system"). (the
only inconsistency is that "kg" as a base unit already has a multiplicator
with it. but one can live with that... :)  


>Meter (m) doesn't make confusion with milli (m) since
>milli alone doesn't exist. It is quantifying some other
>unit, as Volts, grams, even meters (mV, mg, mm).

and to make things clear the upper and lower case =is= significant. not
always, often it is actually redundant if the context is clear, but you
never know... somebody else might think in a different context.

>It is incorrect use the letter "u" for micro, but as
>it doesn't make any confusion with anything else, and
>as the symbol "�" is not available directly at the
>keyboard, we understand and don't care... grrrr!

i mostly use (windows) "US International" which has a lot of the nifty
characters (including all the portuguese accents and tildes :) and switches
easily back and forth between it and the normal US keyboard (eg. for
programming). 

>Degrees use the "�" symbol, as �F or �C, to type it
>just press and hold ALT+SHIFT and type 0 1 7 6 at the
>numeric keypad.

if you type it on the numeric keypad, you don't need the shift (only the
alt key) -- at least with num lock on and on my keyboard.

on the US International � is <right-alt><shift>;

>The same for "�" ALT+SHIFT+0181 (not 181)  => is <right-alt>m
>             "�" ALT+SHIFT+0189 => is <right-alt>7
>             "�" ALT+SHIFT+0188 => is <right-alt>6
>             "�" ALT+SHIFT+0190 => is <right-alt>8

but there might be a problem with these characters. they are not standard
(7bit) ascii, so some non-windows recipients may actually see garbage here.
is that a problem or are such characters within the accepted use policy? :)

ge