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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 permanent magnet is an object made from a material ...
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 . The most familiar effects occur in ferromagnetic ...
Diamagnetism is the property of materials that are repelled by a magnetic field; an applied magnetic field creates an induced magnetic field in them in the opposite direction, causing a repulsive force. In contrast, paramagnetic and ferromagnetic materials are attracted by a magnetic field. Diamagnetism is a quantum mechanical effect that ...
The Earth's magnetic field at 0.5 gauss is too weak to magnetize a lodestone by itself. [9] [10] The leading theory is that lodestones are magnetized by the strong magnetic fields surrounding lightning bolts. [9] [10] [11] This is supported by the observation that they are mostly found near the surface of the Earth, rather than buried at great ...
For example, the number of field lines through a given surface is the surface integral of the magnetic field. [10]: 237 Various phenomena "display" magnetic field lines as though the field lines were physical phenomena. For example, iron filings placed in a magnetic field form lines that correspond to "field lines".
Faraday's law states that the emf is also given by the rate of change of the magnetic flux: where is the electromotive force (emf) and ΦB is the magnetic flux . The direction of the electromotive force is given by Lenz's law . The laws of induction of electric currents in mathematical form was established by Franz Ernst Neumann in 1845.
Magnetic separation is the process of separating components of mixtures by using a magnet to attract magnetic substances. [1] The process that is used for magnetic separation separates non-magnetic substances from those which are magnetic. This technique is useful for the select few minerals which are ferromagnetic (iron-, nickel-, and cobalt ...
An example of a permanent magnet formed from a ferromagnetic material is a refrigerator magnet. [ 2 ] Substances respond weakly to three other types of magnetism— paramagnetism , diamagnetism , and antiferromagnetism —but the forces are usually so weak that they can be detected only by lab instruments.