Re: Capacitance HELP

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: Mddeming@xxxxxxx 

Hi Al,

Welcome to the wonderful world of inconsistencies!

F= Farad= Basic Unit
uF=microfarad =10^ -6 Farad
nF=nanofarad = 10^ -9 Farad
pF=picofarad = 10^ -12 Farad

 The u is actually a typewriter approximation of the Greek letter 
mu. In some literature and on some older components you will see this 
written as mfd, which, for consistency should be millifarads, just as 
mH is millihenries, but it is sort of "commonly known" that m stands 
for micro in capacitors and for milli everywhere else in the world. 
Likewise you will see the terms mmfd or uufd (micromicro-) in place 
of picofarad in many texts. It is an inconsistency that grew out of 
the fact that most early radio techs experimenters, and component 
salesmen, had little education beyond high school and thus (in the 
U.S. at least) had no knowledge of the Greek alphabet other than 
Pi=3.14.... There is a similar mess in the natural gas industry where 
M means Mega for everything except volume, where Mcf means a thousand 
cubic feet rather than a million, because even H.S grads know M is 
the Roman numeral for a thousand.

It's one of those things that you just have to memorize.

Matt D.



In a message dated 1/15/06 12:15:24 A.M. Eastern Standard Time, 
tesla@xxxxxxxxxx writes:

HI List
From
Al Scott
Ok Here goes
UF - what does the u stand for if the f stands for Farads
i know there is nanofarads =NF
Picofarads = PF
When you use the capacitance formula for a plate type cap your answer
is in Picofarads,
now if i wanted to make a cap with a value of 30NF my problem is i
would like to know what
all of the different units are - UF,PF,NF,MF,F,MFD, ect.and in what
order and where they are
before and after the decimal point.
How many PF's are in a UF or NF
which one of these is closest to the right of the decimal point and
what ones are the farthest
and what ones are in between and in what order and what ones did i mis if any.

Like a metric ruler you have MM  CM  ect. right up to Km or what ever
is before MM
I have always hated metric
Thanks in Advance