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Ferrofluid is a liquid that is attracted to the poles of a magnet. It is a colloidal liquid made of nanoscale ferromagnetic or ferrimagnetic particles suspended in a carrier fluid (usually an organic solvent or water). [1] Each magnetic particle is thoroughly coated with a surfactant to inhibit clumping. Large ferromagnetic particles can be ...
The term magnet is typically reserved for objects that produce their own persistent magnetic field even in the absence of an applied magnetic field. Only certain classes of materials can do this. Most materials, however, produce a magnetic field in response to an applied magnetic field – a phenomenon known as magnetism.
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 ...
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.
Neodymium magnets (an alloy, Nd 2 Fe 14 B) are the strongest permanent magnets known. A neodymium magnet of a few tens of grams can lift a thousand times its own weight, and can snap together with enough force to break bones. These magnets are cheaper, lighter, and stronger than samarium–cobalt magnets.
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 ...
The Earth's natural magnetic forces are considerably weak, measuring at 0.5 gauss and magnetic fields from household electronics can easily exceed it, overpowering the compass needle. Exposure to strong magnets, or magnetic interference can sometimes cause the magnetic poles of the compass needle to differ or even reverse.
In the absence of external pressure the maximum shear strength is about 100 kPa. If the fluid is compressed in the magnetic field direction and the compressive stress is 2 MPa, the shear strength is raised to 1100 kPa. [3] If the standard magnetic particles are replaced with elongated magnetic particles, the shear strength is also improved. [4]