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A magnetic field (sometimes called B-field [1]) is a physical field that describes the magnetic influence on moving electric charges, electric currents, [2]: ch1 [3] and magnetic materials. A moving charge in a magnetic field experiences a force perpendicular to its own velocity and to the magnetic field.
A magnet is a material or object that produces a magnetic field.This magnetic field is invisible but is responsible for the most notable property of a magnet: a force that pulls on other ferromagnetic materials, such as iron, steel, nickel, cobalt, etc. and attracts or repels other magnets.
A magnetic field contains energy, and physical systems move toward configurations with lower energy. When diamagnetic material is placed in a magnetic field, a magnetic dipole tends to align itself in opposed polarity to that field, thereby lowering the net field strength. When ferromagnetic material is placed within a magnetic field, the ...
Within each domain, the spins are aligned, but if the bulk material is in its lowest energy configuration (i.e. "unmagnetized"), the spins of separate domains point in different directions and their magnetic fields cancel out, so the bulk material has no net large-scale magnetic field. Ferromagnetic materials spontaneously divide into magnetic ...
The strength of neodymium magnets is the result of several factors. The most important is that the tetragonal Nd 2 Fe 14 B crystal structure has exceptionally high uniaxial magnetocrystalline anisotropy (H A ≈ 7 T – magnetic field strength H in units of A/m versus magnetic moment in A·m 2).
Ferrofluid on glass, with a rare-earth magnet underneath. A rare-earth magnet is a strong permanent magnet made from alloys of rare-earth elements.Developed in the 1970s and 1980s, rare-earth magnets are the strongest type of permanent magnets made, producing significantly stronger magnetic fields than other types such as ferrite or alnico magnets.
The maximum magnetic field B is about 0.35 tesla and the magnetic field strength H is about 30–160 kiloampere turns per meter (400–2000 oersteds). [33] The density of ferrite magnets is about 5 g/cm 3. The most common hard ferrites are: Strontium ferrite Sr Fe 12 O 19 (Sr O · 6 Fe 2 O
The magnetic field (B, green arrow) of the magnet's North pole N is directed down in the −y direction. The magnetic field exerts a Lorentz force on the electron (pink arrow) of F 1 = −e(v × B), where e is the electron's charge. Since the electron has a negative charge, from the right hand rule this is directed in the +z direction.