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Ancient people learned about magnetism from lodestones (or magnetite) which are naturally magnetized pieces of iron ore.The word magnet was adopted in Middle English from Latin magnetum "lodestone", ultimately from Greek μαγνῆτις [λίθος] (magnētis [lithos]) [1] meaning "[stone] from Magnesia", [2] a place in Anatolia where lodestones were found (today Manisa in modern-day Turkey).
Magnetic field lines form in concentric circles around a cylindrical current-carrying conductor, such as a length of wire. The direction of such a magnetic field can be determined by using the "right-hand grip rule" (see figure at right). The strength of the magnetic field decreases with distance from the wire.
Magnetism is the class of physical attributes that occur through a magnetic field, which allows objects to attract or repel each other.Because both electric currents and magnetic moments of elementary particles give rise to a magnetic field, magnetism is one of two aspects of electromagnetism.
However, magnetic torque magnetometry doesn't measure magnetism directly as all the previously mentioned methods do. Magnetic torque magnetometry instead measures the torque τ acting on a sample's magnetic moment μ as a result of a uniform magnetic field B, τ = μ × B. A torque is thus a measure of the sample's magnetic or shape anisotropy.
The magnetization field or M-field can be defined according to the following equation: =. Where is the elementary magnetic moment and is the volume element; in other words, the M-field is the distribution of magnetic moments in the region or manifold concerned.
Carl Friedrich Gauß in 1828, aged 50 years old. The gauss (symbol: G, sometimes Gs) is a unit of measurement of magnetic induction, also known as magnetic flux density.The unit is part of the Gaussian system of units, which inherited it from the older centimetre–gram–second electromagnetic units (CGS-EMU) system.
Because magnetic monopoles do not exist, the magnetic field at a large distance from any static magnetic source looks like the field of a dipole with the same dipole moment. For higher-order sources (e.g. quadrupoles) with no dipole moment, their field decays towards zero with distance faster than a dipole field does.
These magnetic fields are a hundred million times stronger than any man-made magnet, [11] and about a trillion times more powerful than the field surrounding Earth. [12] Earth has a geomagnetic field of 30–60 microteslas, and a neodymium-based, rare-earth magnet has a field of about 1.25 tesla, with a magnetic energy density of 4.0 × 10 5 J/m 3.