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Gaussian & cgs emu a
Conversion factor, C b
SI & rationalized mks c
Magnetic flux density, magnetic induction
gauss (G) d
tesla (T), Wb/m2
maxwell (Mx), Gּcm2
weber (Wb), volt second (Vּs)
Magnetic potential difference,magnetomotive force
Magnetic field strength, magnetizing force
oersted (Oe),e Gb/cm
(Volume) magnetization g
Magnetic polarization, intensity of magnetization
4π x 10-4
T, Wb/m2 i
14π x 10-7
Aּm2, joule per tesla (J/T)
Magnetic dipole moment
4π x 10-10
4π(4π)2 x 10-7
dimensionlesshenry per meter (H/m), Wb/(Aּm)
4π x 10-3(4π)2 x 10-10
4π x 10-6(4π)2 x 10-13
4π x 10-7
Relative permeability j
(Volume) energy density, energy product k
a. Gaussian units and cgs emu are the same for magnetic properties. The defining relation is B = H + 4πM.
b. Multiply a number in Gaussian units by C to convert it to SI (e.g., 1 G x 10-4 T/G = 10-4 T).
c. SI (Système International d’Unitès) has been adopted by the National Bureau of Standards.Where to conversion factors are given, the upper one is recognized under, or consistent with, SI and is based on the definition B = μo(H + M), where μo = 4π x 10-7 H/m. The lower one is not recognized under SI and is based on the definition B = μoH + J, where the symbol I is often used in place of J.
d. 1 gauss = 105 gamma (γ).
e. Both oersted and gauss are expressed as cm-1/2ּg1/2ּs-1 in terms of base units.
f. A/m was often expressed as “ampere-turn per meter” when used for magnetic field strength.
g. Magnetic moment per unit volume.
h. The designation “emu” is not a unit.
i. Recognized under SI, even though based on the defition B = μoH + J. See footnote c.
j. μr = μ/μo = 1 + χ, all in SI. μr is equal to Gaussian μ.
k. BּH and μoMּH have SI units J/m3; MּH and BּH/4π have Gaussian units erg/cm3.
This information was taken with permission from R. B. Goldfarb and F. R. Fickett, U.S. Department of Commerce, National Bureau of Standards, Boulder, Colorado 80303, March 1985, NBS Special Publication 696.