Magnetometers used to study the Earth's magnetic field may express the vector components of the field in terms of declination (the angle between the horizontal component of the field vector and true, or geographic, north) and the inclination (the angle between the field vector and the horizontal surface). Total field magnetometers or scalar magnetometers measure the magnitude of the vector magnetic field. Vector magnetometers measure the vector components of a magnetic field. There are two basic types of magnetometer measurement. The spacecraft uses two fluxgate magnetometers. Types of magnetometer The Magnetometer experiment for the Juno orbiter for Juno can be seen here on the end of a boom. 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. Gaussmeters and teslameters are magnetometers that measure in units of gauss or tesla, respectively. ![]() 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 anomalies can be in the picotesla (pT) range. ![]() Measurements of the Earth's magnetic field are often quoted in units of nanotesla (nT), also called a gamma. The strength of a magnetic field is measured in units of tesla in the SI units, and in gauss in the cgs system of units. Magnetic fields are vector quantities characterized by both strength and direction. In recent years, magnetometers have been miniaturized to the extent that they can be incorporated in integrated circuits at very low cost and are finding increasing use as miniaturized compasses ( MEMS magnetic field sensor). Magnetometers are capable of detecting large objects, such as cars, at over 10 metres (33 ft), while a conventional metal detector's range is rarely more than 2 metres (6 ft 7 in). Magnetometers can be used as metal detectors: 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. Consequently, some countries, such as the United States, Canada and Australia, classify the more sensitive magnetometers as military technology, and control their distribution. Magnetometers are also used by the military as a triggering mechanism in magnetic mines to detect submarines. In an aircraft's attitude and heading reference system, they are commonly used as a heading reference. Magnetometers are widely used for measuring the Earth's magnetic field, in geophysical surveys, to detect magnetic anomalies of various types, and to determine the dipole moment of magnetic materials. The first magnetometer capable of measuring the absolute magnetic intensity at a point in space was invented by Carl Friedrich Gauss in 1833 and notable developments in the 19th century included the Hall effect, which is still widely used. 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. A compass is one such device, one that measures the direction of an ambient magnetic field, in this case, the Earth's magnetic field. ![]() Different types of magnetometers measure the direction, strength, or relative change of a magnetic field at a particular location. ![]() Helium vector magnetometer (HVM) of the Pioneer 10 and 11 spacecraftĪ magnetometer is a device that measures magnetic field or magnetic dipole moment.
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