Editing Magnetometer (section)

===Magnetic fields===
Magnetic fields are [[vector (mathematics)|vector]] quantities characterized by both strength and direction. The strength of a magnetic field is measured in units of [[tesla (unit)|tesla]] in the [[SI unit]]s, and in [[gauss (unit)|gauss]] in the [[cgs system]] of units. 10,000 gauss are equal to one tesla.<ref name=Macintyre2000>{{cite web|last=Macintyre|first=Steven A.|title=Magnetic field measurement.|url=http://engineering.dartmouth.edu/dartmag/docs/macintyre.pdf|work=ENG Net Base (2000)|publisher=CRC Press LLC|access-date=29 March 2014|archive-date=19 March 2015|archive-url=https://web.archive.org/web/20150319010220/http://engineering.dartmouth.edu/dartmag/docs/macintyre.pdf|url-status=dead}}</ref> Measurements of the Earth's magnetic field are often quoted in units of nanotesla (nT), also called a gamma.<ref name="FS–236–95">{{cite web|title=USGS FS–236–95: Introduction to Potential Fields: Magnetics|url=http://pubs.usgs.gov/fs/fs-0236-95/fs-236-95.pdf|publisher=USGS|access-date=29 March 2014}}</ref> The Earth's magnetic field can vary from 20,000 to 80,000 nT depending on location, fluctuations in the Earth's magnetic field are on the order of 100 nT, and magnetic field variations due to [[magnetic anomaly|magnetic anomalies]] can be in the picotesla (pT) range.<ref name=Hovde2013>{{cite book|author1=D. C. Hovde|author2=M. D. Prouty|author3=I. Hrvoic|author4=R. E. Slocum|title="Commercial magnetometers and their application", in the book "Optical Magnetometry"|date=2013|publisher=Cambridge University Press|isbn=978-0-511-84638-0|pages=387–405|url=http://ebooks.cambridge.org/chapter.jsf?bid=CBO9780511846380&cid=CBO9780511846380A137&tabName=Chapter|access-date=30 March 2014|archive-date=7 April 2014|archive-url=https://web.archive.org/web/20140407080700/http://ebooks.cambridge.org/chapter.jsf?bid=CBO9780511846380&cid=CBO9780511846380A137&tabName=Chapter|url-status=dead}}</ref> ''Gaussmeters'' and ''teslameters'' are magnetometers that measure in units of gauss or tesla, respectively. In some contexts, magnetometer is the term used for an instrument that measures fields of less than 1 millitesla (mT) and gaussmeter is used for those measuring greater than 1 mT.<ref name=Macintyre2000/>