GMW BARTINGTON MAG-03, Руководство по эксплуатации

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OM1004 ISSUE 20 PAGE 15 OF 30
10.2 MEASUREMENT UNITS
Since 1960 the SI (Systeme Internationale) which is derived from the MKS metric
measurement system has been universally adopted. However, measurements are still
frequently expressed in the older CGS units. For clarity the following relationships may be
useful.
The fundamental equation describing the relationship between magnetic field strength H,
magnetic flux density B and the permeability of free space
μ
o is:
B =
μ
oH
SI is the preferred system of measurement in this manual and these units, together with their
CGS numerical (but not dimensional) equivalents, are shown in the left hand column below.
SI = CGS
B Wbm
-2
(Weber per metre
2
) 10
4
G (Gauss)
or T (Tesla)
H Am
-1
(Amperes per metre) 4
π
x 10
-3
(Oe)
It will be seen that the term 4
π
occurs in the CGS units. The SI units, however, are
rationalised indirectly by incorporating this term in
μ
o. Thus in the SI system:
μ
o = 4
π
x 10
-7
Hm
-1
(Henries per metre).
Example: For free space If H = 80 Am
-1
Then B = 4
π
x 10
-7
x 80
≈
1 x 10
-4
T
Tesla is the preferred unit for flux density in the SI system. A magnetic field sensor can only
be said to measure flux density.
10.3 CONVERSION TABLE
The most common conversion performed will be from Tesla to Gauss and vice-versa. The
following table may be helpful.
SI CGS CGS SI
1 Tesla 10 kGauss 1 kGauss 100 mTesla
1 mT 10 G 1 G
100
μ
T
1
μ
T
10 mG 1 mG 100 nT
1 nT
10
μ
G 1
μ
G
100 pT
TABLE 3 CONVERSION OF SI AND CGS UNITS