Gauss (unit)

Name, symbol, and metric prefixes

Although not a component of the International System of Units, the usage of the gauss generally follows the rules for SI units. Since the name is derived from a person's name, its symbol is the uppercase letter "G". When the unit is spelled out, it is written in lowercase ("gauss"), unless it begins a sentence. The gauss may be combined with metric prefixes, such as in milligauss, mG (or mGs), or kilogauss, kG (or kGs).

Unit conversions

\begin{align} 1,{\rm G} &= {\rm Mx}{\cdot}{\rm cm}^{-2} = \frac{\rm g}{{\rm Bi}{\cdot}{\rm s}^2}\ &\text{ ≘ } 10^{-4},{\rm T} = 10^{-4}\frac{\rm kg} \end{align}

The gauss is the unit of magnetic flux density B in the system of Gaussian units and is equal to Mx/cm2 or g/Bi/s2, while the oersted is the unit of H-field. One tesla (T) corresponds to 104 gauss, and one ampere (A) per metre corresponds to 4π × 10−3 oersted. A biot (or abampere) is equal to 10 amperes.

The units for magnetic flux Φ, which is the integral of magnetic B-field over an area, are the weber (Wb) in the SI and the maxwell (Mx) in the CGS-Gaussian system. The conversion factor is , since flux is the integral of field over an area, area having the units of the square of distance, thus (magnetic field conversion factor) times the square of (linear distance conversion factor). 108 Mx/Wb = 104 G/T × (102 cm/m)2.

Typical values

Main article: Orders of magnitude (magnetic field)

• 10−9–10−8 G – the magnetic field of the human brain
• 10−6–10−3 G – the magnetic field of Galactic molecular clouds. Typical magnetic field strengths within the interstellar medium of the Milky Way are ~5 μG.
• 0.25–0.60 G – the Earth's magnetic field at its surface
• 4 G – near Jupiter's equator
• 25 G – the Earth's magnetic field in its core
• 50 G – a typical refrigerator magnet
• 100 G – an iron magnet
• 1500 G – within a sun spot
• 10000 to 13000 G – remanence of a neodymium-iron-boron (NIB) magnet
• 16000 to 22000 G – saturation of high permeability iron alloys used in transformers
• 3000–70000 G – a medical magnetic resonance imaging machine
• 1012–1013 G – the surface of a neutron star
• 4 × 1013 G – the Schwinger limit
• 1014 G – the magnetic field of SGR J1745-2900, orbiting the supermassive black hole Sgr A* in the center of the Milky Way.
• 1015 G – the magnetic field of some newly created magnetars{{cite web |access-date = 2007-05-23 |url-status = dead |archive-url = https://web.archive.org/web/20070611144512/http://solomon.as.utexas.edu/~duncan/magnetar.html#Epilog |archive-date = 2007-06-11
• 1017 G – the upper limit to neutron star magnetism

Notes

References

References

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2. ''NIST Special Publication 1038'', Section 4.3.1
3. {{SIbrochure9th
4. {{SIbrochure8th
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6. Jackson, John (1975), ''Classical Electrodynamics, 2nd Ed.'', John Wiley, {{ISBN. 0-471-43132-X
7. Buffett, Bruce A. (2010), "Tidal dissipation and the strength of the Earth's internal magnetic field", ''Nature'', volume 468, pages 952–954, {{doi. 10.1038/nature09643
8. Hoadley, Rick. "How strong are magnets?".
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11. "How strong are magnets?". Magcraft.