b & B, k & K, m & M; was BSO on the radio - not for me anymore

Garrett Wollman wollman@bimajority.org
Sat Oct 16 00:46:03 EDT 2010

<<On Fri, 15 Oct 2010 22:26:29 -0400, "Dave Doherty" <dave@skywaves.net> said:

> Let us not lose sight of the fact that many of our units are based on 
> historical figures, and these should always be capitalized:

> Watt:  uW., mW, W, kW, MW
> Bell:  dB, dBu, dBk, dBi
> Volt: uV, mV, V, kV, MV
> Ampere: uA, mA, A

It's more complicated than that.

The names of the full units are *never* capitalized.  Only the symbols
are capitalized -- but only for units named after people: symbols for
units which are not named after people must not be capitalized.

The bel (note one "l") is not an official SI unit; another logarithmic
unit is the neper (Np), which is based on natural, rather than common,
logarithms, and the neper is "accepted for use with the SI" although
it is not an official SI unit (being dimensionless).  The SI symbol
for the prefix "micro-" is the Greek letter µ (U+00B5 or U+03BC), but
ISO 2955:1983 ("Representation of SI and other units in systems with
limited character sets") permits the use of the roman letter "u";
traditionally the sequence "mc" was used.  (ISO 2955 also specifies
that the word "Ohm" may be used if the capital omega is not
available.)  The symbol "S" is for the unit of conductivity, the
siemens, and may not be used for the second.

Other important SI electrical units named after people include the
farad (after Michael Faraday), the henry (after Joseph Henry), the
hertz (after Heinrich Hertz), the joule (after James Joule), the
coulomb (after Charles-Augustin de Coulomb), the tesla (after Nikola
Tesla), and the weber (after Wilhelm Weber).  Non-SI electrical units
include the gauss, the maxwell, the oersted, the franklin, and the


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