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Glossary - M |
Magnetic axis
Magnetic material
Magnetic flux Φ
Magnetic induction (B)
Magnetic pole
Magnetic polarisation (J)
Magnetic shield
Magnetic susceptibility 
Magnetisation M
Magnetiser
Magnetising coil (or fixture)
Magnetizing field
Matching coil
Maxwell (Mx)
Maxwell, James Clerk
Moment, magnetic m
Mu-metal
Magnetic axis
In the electric motor terminology, concerning the cross section of a circular machine, is the axis that divides a pole in two parts. (See neutral axis)
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Magnetic material
Generally, all ferromagnetic materials. They are subdivided in two categories: soft magnetic material (those materials with coercivity less than 1 kA/m) and hard magnetic materials (coercivity higher then 1 kA/m).
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Magnetic flux Φ
The magnetic flux of B over an area S is defined as:
If the magnetic induction B is uniform and constant, perpendicular to coil of N turns and area S, the flux linked to the coil is:
The SI unit of flux is weber (Wb).
1 Wb = 1 T ·m²
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Magnetic induction (B)
The magnetic induction B could be seen as the total magnetic field, resulting from the field originated by electrical currents (H) and field produced by magnetic material (M): B = µ0·(H + M).
The SI unit is the tesla (T): 1 T = 104 G.
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Magnetic pole
Place at which the magnetic flux emerges from the magnet. Magnetic lines comes out from North pole and enter in South pole.
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Magnetic polarisation (J)
It is defined as the product of magnetization M and vacuum permeability: J = µ0·M.
Its unit is tesla.
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Magnetic shield
Protection shield that magnetically “short circuits” the magnetic field to protect the external area from the magnetic field.
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Magnetic susceptibility
It describes the interdependance between magnetisation M and magnetic field strength H:
The susceptibility is correlated to the permeability by the: 
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Magnetisation M
Magnetic moment per volume unit. SI unit is A/m. It is the magnetic field produced by magnetic matter.
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Magnetiser
Device that stores and discharges energy on a coil to produce a magnetic field, with the aim to magnetize a permanent magnet or a device containing permanent magnet. Modern magnetisers contains capacitors that are charged to a voltage V (energy = ½CV2) and could be switched to discharge stored energy in form of a pulse of current in a magnetizing coil.
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Magnetising coil (or fixture)
This generates an intense magnetic field to magnetise a permanent magnets or a device containing permanent magnets. This may be in the form of a standard magnetising fixture or more often a fixture designed specifically for a magnetising application. It is highly dependent upon the magnet to be magnetised.
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Magnetizing field
Magnetic field created or used with the aim of magnetize a magnetic material. It is most commonly produced by a current flowing through a coil of wire and its magnitude is proportional to the current, and to the number of turns.
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Matching coil
Coil fed by a matching transformer, with the aim to reduce the voltage monitoring the magnetising current.
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Maxwell (Mx)
The CGS unit of magnetic flux. 1 Mx = 10-8 Wb
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Maxwell, James Clerk
Scottish physicist best known for his formulation of electromagnetic theory. He is regarded by most modern physicists as the scientist of the 19th century who had the greatest influence on 20th-century physics, and he is ranked with Sir Isaac Newton and Albert Einstein for the fundamental nature of his contributions.
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Moment, magnetic m
For a current loop, it is the product of the current and the area of the loop. The direction is perpendicular to the surface of the loop. SI units is A×m2.
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Mu-metal
Fe-Ni alloy (77 % Ni, 17 % Fe, 5 Cu, 1 % Cr) with very low coercivity (Hc ≈ 1 ÷ 4 A/m) and high permeability ( µ, up to 100000). It is used for magnetic shields.
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