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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.
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 that is magnetized and
When these magnetic dipoles in a piece of matter are aligned (point in the same direction), their individually tiny magnetic fields add together to create a much larger macroscopic field. However, materials made of atoms with filled electron shells have a total dipole moment of zero: because the electrons all exist in pairs with opposite spin ...
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 ...
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
After magnetization, items made out of these alloys will remain magnetized depending on their remanence and coercivity. [ 2 ] [ 3 ] Samarium–cobalt magnets are made from an alloy of samarium and cobalt , known for their high magnetic strength, excellent temperature stability and resistance to demagnetization. [ 4 ]
A coil without a magnetic core is called an "air core" coil. Adding a piece of ferromagnetic or ferrimagnetic material in the center of the coil can increase the magnetic field by hundreds or thousands of times; this is called a magnetic core. The field of the wire penetrates the core material, magnetizing it, so that the strong magnetic field ...
Heating a magnet, subjecting it to vibration by hammering it, or applying a rapidly oscillating magnetic field from a degaussing coil, tends to pull the domain walls free from their pinned states, and they will return to a lower energy configuration with less external magnetic field, thus "demagnetizing" the material.