Orders of magnitude

This page lists examples of magnetic field B in tesla produced by various different sources. They are grouped by orders of magnitude, and each section covers three orders of magnitude, or a factor of one thousand.

Note:

• Traditionally, magnetizing field H, is measured in amperes per meter. Magnetic field B (also known as magnetic flux density or magnetic induction) has SI units teslas. One tesla is equal to 10⁴ gauss.
• Magnetic field drops off as the cube of the distance from the source (for a dipole). These examples attempt to make the measuring point clear, usually the surface of the item mentioned.

Below 1 tesla

Attoteslas (10⁻¹⁸ tesla)

• 5 aT -SQUID magnetometers on Gravity Probe B gyros measure fields at this level over several days of averaged measurements ^[1]

Femtoteslas (10⁻¹⁵ tesla)

• 2 fT -SQUID magnetometers on Gravity Probe B gyros measure fields at this level in about one second

Picoteslas (10⁻¹² tesla)

• 0.1 - 1.0 pT - human brain magnetic field
• 10 pT (1.0×10⁻¹¹ tesla) - In September 2006, NASA found "potholes" in the magnetic field in the heliosheath around our solar system that are 10 picoteslas as reported by Voyager 1^[2]

Nanoteslas (10⁻⁹ tesla)

• 0.1 nT to 10 nT - magnetic field strength in the heliosphere

Microteslas (10⁻⁶ tesla)

• 31 µT (3.1×10⁻⁵ T) - strength of Earth's magnetic field at 0° latitude (on the equator)
• 58 µT (5.8×10⁻⁵ T) - strength of Earth's magnetic field at 50° latitude

Milliteslas (10⁻³ tesla)

• 0.5 mT - the suggested exposure limit for cardiac pacemakers by American Conference of Govenmental Industrial Hygienists (ACGIH)
• 5 mT - the strength of a typical refrigerator magnet [2]
• 150 mT (0.15 tesla) - the magnetic field strength of a sunspot

Between 1 and 1000 teslas

The strongest (non-pulsed) magnet in the world is located at NHMFL in Tallahassee, Florida, USA.

tesla

• 1 T to 2.4 T - coil gap of a typical loudspeaker magnet^[3].
• 1.25 T - strength of a modern neodymium-iron-boron (Nd₂Fe₁₄B) rare earth magnet. A coin-sized neodymium magnet can lift more than 9 kg, can pinch skin and erase credit cards.^[4]
• 1.5 T to 3 T - strength of medical magnetic resonance imaging systems in practice, experimentally up to 8 T^[5][6]
• 9.4 T - Modern high resolution research magnetic resonance imaging system
• 11.7 T – field strength of a 500 MHz NMR spectrometer
• 16 T - strength used to levitate a frog^[7]
• 45 T - strongest continuous magnetic field yet produced in a laboratory (Florida State University's National High Magnetic Field Laboratory in Tallahassee, USA)^[8].
• 100 T - strongest (pulsed) magnetic field yet obtained non-destructively in a laboratory (Los Alamos National Laboratory)^[9][10]

Above 1000 teslas

Kilotesla (10³ tesla)

• 2.8 kT - strongest (pulsed) magnetic field ever obtained (with explosives) in a laboratory (VNIIEF in Sarov, Russia, 1998)^[11]

Megateslas (10⁶ tesla)

• 1 to 100 MT (10⁶ T to 10⁸ T) - strength of a neutron star

Gigateslas (10⁹ tesla)

• 0.1 to 100 GT (10⁸ to 10¹¹ T) - strength of a magnetar

References

1. ^ [1]^{[dead link]} Gravity Probe B
2. ^ "Surprises from the Edge of the Solar System". NASA. 2006-09-21. http://science.nasa.gov/headlines/y2006/21sep_voyager.htm?list823631. 
3. ^ Elliot, Rod. "Power Handling Vs. Efficiency". http://sound.westhost.com/articles/pwr-vs-eff.htm. Retrieved 2008-02-17. 
4. ^ The Tesla Radio Conspiracy
5. ^ Smith, Hans-Jørgen. "Magnetic resonance imaging". Medcyclopaedia Textbook of Radiology. GE Healthcare. http://www.medcyclopaedia.com/library/radiology/chapter04/4_5.aspx. Retrieved 2007-03-26. 
6. ^ Orenstein, Beth W. (2006-02-16), "Ultra High-Field MRI — The Pull of Big Magnets", Radiology Today 7 (3): 10, http://www.radiologytoday.net/archive/rt21606p10.shtml, retrieved 2008-07-10 
7. ^ "Frog defies gravity". http://www.newscientist.com/article/mg15420771.600-frog-defies-gravity.html. 
8. ^ "World's Most Powerful Magnet Tested Ushers in New Era for Steady High Field Research". National High Magnetic Field Laboratory. http://www.magnet.fsu.edu/mediacenter/news/pressreleases/1999december17.html. 
9. ^ "Laboratory sets high magnetic field records". LANL. 2006-08-31. http://www.lanl.gov/news/index.php?fuseaction=home.story&story_id=8912. 
10. ^ "One-of-a-kind magnet open for science". PhysOrg.com. 2006-10-25. http://www.physorg.com/news81016852.html. 
11. ^ "With record magnetic fields to the 21st Century". IEEE Xplore. http://ieeexplore.ieee.org/xpl/freeabs_all.jsp?arnumber=823621.