Jesse Mazer wrote:



Franz Heymann wrote:

"Jesse Mazer" wrote in message
...


Franz Heymann wrote:



"Jesse Mazer" wrote in message
...




Franz Heymann wrote:





"Jesse Mazer" wrote in message
...






I wrote:







Well, you're thinking about it wrong. It would be possible to






choose






units of mass such that the gravitational constant G was equal


to






1,






but that wouldn't make it any less real as a physical
constant--similarly, in cgs units, the basic units of charge




(emu)






Sorry, that should be esu...emu is the unit of magnetic charge


in






cgs units.

You might know what you were trying to say both in the original
statement and the correction.
I doubt if anybody else would.
Comment on this garbage, for instance
"emu is the unit of magnetic charge in cgs units"





OK, magnetic moment, I confused my terms, Jeez. I think you know




what I




meant.




No. I had not the foggiest notion. I still do not know what you


are


trying to say.
How about being effective by giving a complete sentence with the
phrase "magnetic moment" in its apropriate place.
If I were to just replace "magnetic charge" by "magnetic moment",


the


sentence would still be garbage, so I feel sure you must be meaning
something else.

Franz






You think the sentence "emu is the unit of magnetic moment in cgs


units"


is garbage?



Yes, assuredly.
The emu, is a generic term which is the name for a complete set of
units encompassing all magnetic and all electrostatic quantities.
What emu is *not* is what you refer to as "the unit of magnetic moment
in cgs units. Moreover there are two differently sized units for
magnetic moment in cgs, namely the cgs emu of magnetic moment and the
cgs esu of magnetic moment.

Have a look at this page:


http://www.unc.edu/~rowlett/units/cgsmks.html

It says that emu is the unit of the magnetic dipole moment in CGS


units,


and that the conversion from CGS to SI is 1 emu = 0.001


Ampere*meter^2.

I don't need to.
What it should say is that 1 emu *of magnetic moment* is the unit of
magnetic dipole moment.
And yes, the conversion factor is correct.

Franz





Well, I was just going by what I read on various webpages describing
units, as I said I'm not an expert on different unit systems. I
checked my E&M textbook, and they don't list any special unit for
magnetic moment, so what you say seems plausible--does that mean the
units for magnetic moment in the e.m.u. system would be
abampere*second*cm, and in the e.s.u. system it'd be statampere*second*cm?

Jesse

By the way, is it also true that if you want to refer to electrical
charge in the cgs system, you should say "1 esu of charge" rather than
just "1 esu"? In my textbook "Introduction to Electrodynamics" by David
Griffiths, on p. 518 there is a table of conversion factors where it is
said that the coulomb in the SI system should be converted to the unit
"esu (statcoulomb)" in the cgs system. Is "statcoulomb" really the unit
of charge in the esu. subsystem of cgs units, and "1 esu of charge" is
just a common shorthand for "1 statcoulomb"?

Jesse