Editing Magnetometer (section)

{{short description |Device that measures magnetism}}
{{Use dmy dates |date=July 2019}}
[[File:Pioneer 10-11 - P50 - fx.jpg |thumb |right |Helium vector magnetometer (HVM) of the [[Pioneer 10]] and [[Pioneer 11|11]] spacecraft]]

A '''magnetometer''' is a device that measures [[magnetic field]] or [[magnetic dipole moment]]. Different types of magnetometers measure the direction, strength, or relative change of a magnetic field at a particular location. A [[compass]] is one such device, one that measures the direction of an ambient magnetic field, in this case, the [[Earth's magnetic field]]. Other magnetometers measure the magnetic dipole moment of a magnetic material such as a [[ferromagnet]], for example by recording the effect of this [[magnetic dipole]] on the induced current in a coil.

The invention of the magnetometer is usually credited to [[Carl Friedrich Gauss]] in 1832.<ref>{{Cite encyclopedia |title=magnetometer |encyclopedia=[[Encyclopaedia Britannica]] |url=https://www.britannica.com/technology/magnetometer |access-date=2025-04-20 |publication-date=1998}}</ref><ref>{{Cite web |title=Magnetometer – 1832 |url=https://nationalmaglab.org/magnet-academy/history-of-electricity-magnetism/museum/magnetometer-1832/ |access-date=2025-04-20 |website=Magnet Academy |publisher=[[National High Magnetic Field Laboratory]]}}</ref> Earlier, more primitive instruments were developed by [[Christopher Hansteen]] in 1819,<ref>{{Cite journal |title=Hansteen's magnetometer and the origin of the magnetic crusade |journal=[[The British Journal for the History of Science]] |date=2014 |last=Enebakk |first=Vidar |volume=47 |issue=4 |pages=587–608 |doi=10.1017/S0007087413000903 |pmid=25546997 }}</ref> and by [[William Scoresby]] by 1823.<ref>{{Cite journal |title=Description of a Magnetimeter, being a New Instrument for Measuring Magnetic Attractions, and Finding the Dip of the Needle; with an Account of Experiments made with it |date=1823 |journal=Transactions of the Royal Society of Edinburgh |last=Scoresby |first=William |url=https://ia800805.us.archive.org/view_archive.php?archive=/13/items/crossref-pre-1909-scholarly-works/10.1017%252Fs0261340900024784.zip&file=10.1017%252Fs0263593300037615.pdf |volume=9 |issue=1 |pages=243–258 |author-link=William Scoresby |doi=10.1017/S0263593300037615}}</ref>

[[File:Mag deply 1219.jpg|thumb|A marine technician prepares a towed magnetometer for deployment from a ship]]
Magnetometers are widely used for measuring the Earth's magnetic field, in [[geophysical survey]]s, to detect [[magnetic anomaly |magnetic anomalies]] of various types, and to determine the dipole moment of magnetic materials. In an aircraft's [[attitude and heading reference system]], they are commonly used as a [[Heading (navigation) |heading]] reference. Magnetometers are also used by the military as a triggering mechanism in magnetic mines to detect submarines. Consequently, some countries, such as the United States, Canada and Australia, classify the more sensitive magnetometers as military technology, and control their distribution.

Magnetometers can be used as [[metal detector]]s: they can detect only magnetic ([[ferrous]]) metals, but can detect such metals at a much greater distance than conventional metal detectors, which rely on conductivity. Magnetometers are capable of detecting large objects, such as cars, at over {{convert|10|m}}, while a conventional metal detector's range is rarely more than {{convert|2|m}}.

In recent years, magnetometers have been miniaturized to the extent that they can be incorporated in [[integrated circuit]]s at very low cost and are finding increasing use as miniaturized compasses ([[MEMS magnetic field sensor]]).