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A magnet's North pole is defined as the pole that is attracted by the Earth's North Magnetic Pole, in the arctic region, when the magnet is suspended so it can turn freely. Since opposite poles attract, the North Magnetic Pole of the Earth is really the south pole of its magnetic field (the place where the field is directed downward into the ...
Illustration of the dynamo mechanism that generates the Earth's magnetic field: convection currents of fluid metal in the Earth's outer core, driven by heat flow from the inner core, organized into rolls by the Coriolis force, generate circulating electric currents, which supports the magnetic field.
A permanent magnet in such a field rotates so as to maintain its alignment with the external field. Magnetic torque is used to drive electric motors. In one simple motor design, a magnet is fixed to a freely rotating shaft and subjected to a magnetic field from an array of electromagnets. By continuously switching the electric current through ...
The demagnetizing field, also called the stray field (outside the magnet), is the magnetic field (H-field) [1] generated by the magnetization in a magnet.The total magnetic field in a region containing magnets is the sum of the demagnetizing fields of the magnets and the magnetic field due to any free currents or displacement currents.
Title page of 1628 edition. De Magnete, Magneticisque Corporibus, et de Magno Magnete Tellure (On the Magnet and Magnetic Bodies, and on That Great Magnet the Earth) is a scientific work published in 1600 by the English physician and scientist William Gilbert.
The net magnetic moment of the magnet m therefore is =, where the triple integral denotes integration over the volume of the magnet. For uniform magnetization (where both the magnitude and the direction of M is the same for the entire magnet (such as a straight bar magnet) the last equation simplifies to: m = M V , {\displaystyle \mathbf {m ...
Early unsuccessful attempts to reach the magnetic south pole included those of French explorer Jules Dumont d'Urville (1837–1840), American Charles Wilkes (expedition of 1838–1842) and Briton James Clark Ross (expedition of 1839–1843).
As it is known today, there are only a few possible ways to reverse the magnetization of a metallic magnet: an applied magnetic field [5] spin injection via a beam of particles with spin [5] magnetization reversal by circularly polarized light; [6] i.e., incident electromagnetic radiation that is circularly polarized