CGS versus SI

This article is a stub. Please help to improve the relax wiki by expanding the article.

Warning  If hard core NMR or physics theory is not to your taste, please do not read any further!

The SI or International System of Units versus the CGS or Centimetre–gram–second system of units is a constant source of confusion in the field of NMR. Both are based on the metric system, however the differences can result in quite different forms of the fundamental NMR equations. An example of this is Tesla versus Gauss units for the magnetic field strength.

Units of measurement

Quantity	Symbol	SI unit			CGS unit			SI to CGS conversion factor
		Name	Symbol	Base unit	Name	Symbol	Base unit
length	L	metre		m	centimetre		cm	10−2
mass	m	kilogram		kg	gram		g	10−3
time	t	second		s	second		s	1
velocity	v	metre per second		m⋅s−1	centimetre per second		cm⋅s−1	10−2
acceleration	a	Metre per second squared		m⋅s−2	Gal	gal	cm⋅s−2	10−2
force	F	Newton	N	kg⋅m⋅s−2	dyne	dyn	g·cm·s−2	10−5
energy	E	Joule	J	kg⋅m2·s−2	erg	erg	g·cm2·s2	10−7
power	P	Watt	W	kg⋅m2·s−3	erg per second	erg⋅s−1	g·cm2·s−3	10−7
magnetic flux density	B	Tesla	T	kg·s−2·A−1	Gauss	Gs	esu·cm−2	10−4
magnetic flux	H	Weber	Wb	kg·m2·s−2·A−1	Oersted	Oe	g·cm·s−2	1000/4π

Constants

Constant	Symbol	SI unit			CGS unit			SI to CGS conversion factor
		Definition	Value	Base units	Definition	Value	Base units
magnetic force constant	kA	µ0·(4π)−1	10−7	kg⋅m·s−2·A−3		1		4π·µ0−1
magnetic constant	µ0	µ0	4π·10−7	kg·m·s−2·A−3		1		µ0−1