MAGNETIC UNITS CONVERSION



DEFINITIONS, ONLINE CALCULATORS, EQUATIONS IN SI AND CGS


Let's begin by defining some terms.

Magnetic field

is one of two components of the electromagnetic field. Technically speaking, it refers to a region where forces acting on moving electric charges can be detected. Magnetic fields are created by either moving electric charges or variable electric field. The charge movement that creates the field may be macroscopic (currents in conductors), or microscopic. The latter type is associated with spin and orbital motion of electrons, resulting in so-called "magnetic materials".



The SI unit for magnetic flux is the weber (Wb). If this flux changes by 1 Wb over a time of 1s, then a voltage of 1 V is induced in a conductive loop encircling it: 1 Wb = 1 Vs.
The flux density is called induction. The SI magnetic induction unit B is tesla (T): 1 T = 1 Wb/m2 = 1 Vs/m2. Mathematically, magnetic field with density of 1 T generates one newton of force per ampere of current per meter of conductor.
When the fields generated by currents pass through some materials they can produce magnetization in the direction of the applied field. In ferromagnetics it results in increased total field B. Quantity called magnetic field strength (magnetizing force) is a measure of the applied magnetic field from external currents, independent of the material's response. CGS unit of magnetic field strength is oersted, and SI unit is ampere/meter. Magnetisation defines the material's response- it is magnetic moment per unit volume of material. Flux density (magnetic induction) describes the resulting field in the material, which is a combination of an applied field and the magnetization. In power electronics it is the main quantity used in calculation of the required cross-sectional area of power transformer cores for given voltage and frequency (see engineering reference info on power transformer design).
Below you will find converters for the magnetic units and the table with the magnetism formulas and factors in both SI and CGS systems.


MAGNETIC FLUX DENSITY UNIT
CONVERSION CALCULATOR



tesla [T]:
gauss [Gs, G]:
weber/square meter:
weber/square centimeter:
maxwell/square meter:
maxwell/sq. centimeter:
line/square centimeter:
gamma:

MAGNETIC FIELD STRENGTH UNIT
CONVERSION CALCULATOR

ampere/meter [A/m]:
oersted [Oe]:


Calculators' data are courtesy of www.unitconversion.org




QUANTITY SYMBOL SI UNIT SI EQUATION CGS UNIT CGS EQUATION CONVERSION FACTOR
Magnetic
induction		 B tesla (T) B=µo(H+M)
=µrµoH		 gauss (G) B = H+4πM
=µrH 		1 T = 104 G
Magnetic field strength H ampere/ meter
(A/m)		 H = N×I/lc
( lc - magnetic
path, m)		 oersted (Oe) H = 0.4πN×I/lc
(lc - magnetic
path, cm)
 1 A/m =
4π×10-3 Oe
Magnetic flux Φ weber (Wb) Φ = B×Ac
(Ac - area, m2 )		 maxwell (M) Φ = B×Ac
(Ac- area, cm2)		 1 Wb = 108 M
Magnetization M ampere/ meter (A/m) M=m/V
(m- total magnetic moment,
V- volume, m3 )		 emu/cm3 M=m/V
(m- total magnetic moment,
V- volume, cm3 )		 1 A/m = 10-3
emu / cm3
Magnetic permeability
of vacuum		 µo newton/ ampere2
 µo= 4π×10-7 1 - 4π×10-7
Inductance L henry L=μoμN2Ac/lc
(Ac- area, m2,
lc - magnetic path, m)		 henry L=0.4πμN2Ac/lc×10-8
(Ac-area, cm2,
lc - magnetic path, cm)		 1
Emf (voltage) V volt V=-N×dΦ/dt
 volt V=-10-8N×dΦ/dt
 1
Note: in the above equations: N- turns, I - current (in amps)



©2007, 2012 Lazar Rozenblat