Talk:Centimeter gram second system of units

Is this system still in use?
CGS is the still the primary system in use for astrophysics research worldwide and is accepted by all major astronomy/astrophysics journals.

Is this system still in use. To my knowledge nowadays international standards recommend people to use SI which is done in Europe. CGS is still widely used in teaching, textbooks, and research. My experience suggests that the primary users are perhaps older North American scientists, and that CGS may eventually die out, but it will be around for quite a while. The article could be enhanced by adding a table of conversion factors between the various CGS variants and SI units for relevant units. In particular, non-linear susceptibilities can be tricky to convert.

It's used primarily in physics E&M textbooks because the coulomb and tesla are ridiculously large, and in SI they are different units. In CGS, the Gauss is the same as a statvolt/meter. I suppose that it is primarily an informational peice, mainly for completeness.--BlackGriffen

The equations for the force due to magnetic field and other magnetic equations are slightly different in CGS units than SI becuase it includes the speed of light rahter than a constant. CGS units are used in E&M textbooks becuase when using CGS units it is more obvious that magnetic forces are simply a consequence of relativity rather than a phenomena on their own.


 * Math formatting does not seem to be working. Does anyone know why?

It should be mentioned that chemists only recently converted from cgs to SI units. I suspect that it will be a long time before people who work in the lab use kilograms instead of grams.

Even today the lack of mks units for such quantities as magnetic flux density and viscosity leads people to continue using the gauss and the centipoise. —Preceding unsigned comment added by 71.250.142.249 (talk • contribs)


 * Grams are very much a part of SI. Where'd you ever get the idea they are not?  There is no lack of SI units for the quantities you mentioned, either.  In fact, the SI unit corresponding to the gauss is the tesla, like the gauss with a special one-word name.  The SI unit of dynamic viscosity is the pascal second. Gene Nygaard 04:04, 30 March 2006 (UTC)

To my knowledge nobody teaches physics in CGS anymore. Even my American textbooks (I'm in the UK) are mostly referenced in SI units. It surprised me very much that anyone still uses this system. Why? Sojourner001 20:33, 9 August 2006 (UTC)
 * You are completely wrong as for teaching. In Russia, for example, serious EM science is posed exlusively in CGS. —The preceding unsigned comment was added by 83.149.226.126 (talk) 10:05, 9 February 2007 (UTC).

What level of physics? When I took physics classes in the late 1980's, I found that first-year E+M courses all used MKS, but my second-year course used CGS (and was taught by a young professor, contrary to the comments about it being only taught by old professors). The classic Jackson E+M textbook used CGS (2nd edition), and the latest version might still do so (I'm not sure). In many ways it was far more convenient, as you avoided the 4*pi*e0 constants and similar junk. Benwing 04:27, 24 August 2006 (UTC)

I am currently studying Astrophysics at the honours level in Australia, and i'm still being taught in CGS units in some courses. 150.203.111.155 00:25, 28 August 2006 (UTC)

Definition of the centimetre
A centimeter is the capacitance between a 1-cm sphere in vacuum and infinity. Is this true in the CGS system? It doesn't make sense to someone raised on SI units. Could this sentence be better worded to explain why a unit normally used for distance is also a unit of capacitance, please? -- Heron

Gauss
Would anyone object to my removing the 'not used' from Gauss? I, and many others astronomers, use them every day.

More Gauss
He's far better known for his contributions to mathematics IMO he should be referred to as a mathematian rather than an astronomer (readers can read about his many other talents on the Gauss page).


 * Done. Markus Kuhn 13:17, 7 August 2005 (UTC)

Various cgs systems
In his recent edit summary, Crissov stated "clearer distinction between mechanical and electromechanic CGS is needed".

Even allowing for the fact that edit summaries are often cryptic, that is not what is needed. These aren't what need to be "distinguished". The likely reason that the mechanical units are listed separately is not because they need to be distiguished, but rather that they are pretty much common to all the various cgs systems. It is the electrical and magnetic units, and the electromagnetic system, the electromagnetic system, and the hybrid Gaussian system which need to be better distinguished (all sharing the same mechanical units). Another distinction can be made between three-base-unit (with, for example, electrical charge measured in units of erg1/2·cm1/2) and four-base-unit systems using a franklin or a biot as a base unit, and between rationalized and non-rationalized systems. It hurts my head to even try to figure them all out; thank God for the International System of Units. Gene Nygaard 21:30, 24 September 2005 (UTC)

relation of constants
What's wrong: k_1/k_2=c^2 or k_2 in the electrostatic cgs system?


 * Shouldn't k_1/k_2 = c^2/2? GoldenBoar 06:57, 2 June 2006 (UTC)

From PNA/Physics

 * Oersted,Centimetre gram second system of units in my humble opinion those article should at least contain the same information as the appendix of Jackson's electrodynamic --LN2 05:46, 18 February 2006 (UTC)


 * fixed

statcoulomb
The statcoulomb to MKS conversion factor on this page is inconsistent with

http://en.wikipedia.org/wiki/Statcoulomb

I suspect the link above is the correct value, but I have to confirm this.

Britanica confirms:

http://www.britannica.com/eb/article-9032320?query=electric%20charge&ct=

charge of electron = 1.60e-19 coulombs = 4.80 e-10 esu

Therfore 1 esu = 3.33e-10 coulombs, approx. The mistake made on this page was to confuse the charge of the electron, in statcoulombs, with the conversion factor between coulombs and statcoulombs.

Pervect 23:16, 29 July 2006 (UTC)

Suggest removing unreferenced tag
Is the unreferenced tag needed for an article like this? --Ujm 06:34, 18 October 2006 (UTC)

Is there a unit for speed?
If there was, I would guess it would be like centimeters per second or something like that. If this is scientific, it should have speed. —The preceding unsigned comment was added by 66.188.139.109 (talk) 22:56, 2 February 2007 (UTC). not sure what I'm doing but i memorized something i read once and not sure if it is a measure of speed or distance. The cgs unit of magnetic induction that is equal to the magnetic flex density. that will induce an electromotive force of one one hundred millionth of a volt. In each liner centimeter on a wire moving laterally. At one centimeter per second right angles to a magnetic flex

A few questions...
Ok, first of all the definition of the gauss is based on the Maxwell and the definition of the Maxwell is based on the gauss. ?

Also, for anyone who may know, I have a question regarding CGS vs SI units. This textbook I am looking at uses CGS units, and has as the force on a particle due to a magnetic field (qv/c) x B, with B in gauss. This would mean that a gauss would have units Force/charge, same as electric field. But in SI units, the c is not there, and the units for the magnetic field unit, the Tesla, are not Force/charge, but mass/(charge*time) (according to wikipedia 1 Tesla = 1 kg/(C*s). But the book and wikipedia both say that tone tesla equals 10,000 gauss.  How can there be a dimensionless conversion between to quantities with different dimensions?  It would be like saying one second is equal to 54 kilograms, it doesnt make sense to me.  So somewhere that oughta be cleared up thanks —The preceding unsigned comment was added by 165.123.231.59 (talk) 08:30, 6 April 2007 (UTC).