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These so-called ceramic magnets are cheap, and are widely used in household products such as refrigerator 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.
Therefore, ferrofluids, with a max bearing pressure in the order of 2 x 104, have been studied to increase the amount of weight that magnetic force can pull. A study by Hsu [2] demonstrated that a ferrofluid-controlled microrobot was able to carry 130 times the mass of its bare magnet counterpart.
Spin-stabilized magnetic levitation is a phenomenon of magnetic levitation whereby a spinning magnet or array of magnets (typically as a top) is levitated via magnetic forces above another magnet or array of magnets, and stabilised by gyroscopic effect due to a spin rate that is neither too fast, nor too slow to allow for a necessary precession.
This magnetic orientation process replicates that applied by a magnetic recording tape head to the magnetic tape coating during the recording process. The principle was further described by James (Jim) M. Winey of Magnepan in 1970, for the ideal case of continuously rotating magnetization, induced by a one-sided stripe-shaped coil.
Electromagnetic suspension (EMS) is the magnetic levitation of an object achieved by constantly altering the strength of a magnetic field produced by electromagnets using a feedback loop. In most cases the levitation effect is mostly due to permanent magnets as they have no power dissipation, with electromagnets only used to stabilise the effect.
The strongest continuous magnetic fields on Earth have been produced by Bitter magnets. The strongest continuous field achieved solely with a resistive magnet is 41.5 tesla as of 22 August 2017, produced by a Bitter electromagnet at the National High Magnetic Field Laboratory in Tallahassee, Florida. [6] [7]
The magnetic gear is a magnetic coupling device that renders a mechanical ratio between two magnetically-coupled devices such that: They have a ratio of rotational or translational movement between input and output, which may be 1 in the case of a pure magnetic coupling or one of many gear ratios in a magnetic gearbox.
The development of modern rare-earth magnets makes the simple magneto alternator a more practical proposition as a power generator, as these permit a greatly increased field strength. As the magnets are compact and of light weight, they generally form the rotor, so the output windings can be placed on the stator, avoiding the need for brushgear.