Magnetic Field

A magnetic field may be represented by a mathematical description of the magnetic influence of electric currents and magnetic materials. The magnetic field at any given point is specified by both a direction and a magnitude (or strength); as such it is a vector field. The magnetic field is most commonly defined in terms of the Lorentz force it exerts on moving electric charges. There are two separate but closely related fields to which the name "magnetic field" can refer, denoted by the symbols B and H.

Magnetic fields are produced by moving electric charges and the intrinsic magnetic moments of elementary particles associated with a fundamental quantum property, their spin. In special relativity, electric and magnetic fields are two interrelated aspects of a single object, called the electromagnetic tensor; the split of this tensor into electric and magnetic fields depends on the relative velocity of the observer and charge. In quantum physics, the electromagnetic field is quantized and electromagnetic interactions result from the exchange of photons.

Magnetic fields have had many uses in ancient and modern society. The Earth produces its own magnetic field, which is important in navigation. Rotating magnetic fields are utilized in both electric motors and generators. Magnetic forces give information about the charge carriers in a material through the Hall effect. The interaction of magnetic fields in electric devices such as transformers is studied in the discipline of magnetic circuits.

Read more about Magnetic Field:  History, Definitions, Units, and Measurement, Magnetic Field Lines, Magnetic Field and Permanent Magnets, Magnetic Field and Electric Currents, Relation Between H and B, Energy Stored in Magnetic Fields

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High Temperature Scanning SQUID Microscope - Magnetic Field Detection Using SQUID
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Spacecraft Magnetometer - Configurations of Magnetometers - Dual Technique
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High Temperature Scanning SQUID Microscope
... using a YBCO SQUID is capable of measuring magnetic fields as small as 20 pT (about 2 million times weaker than the earth’s magnetic field) ... technique can be used to transform the magnetic field image into an equivalent map of the current in an integrated circuit or printed wiring board ... With this post-processing of a magnetic image and the low noise present in SQUID images, it is possible to enhance the spatial resolution by factors of 5 or more over the near-field limited ...
Coil Knot
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Important Uses and Examples of Magnetic Field - Magnetic Monopole (hypothetical)
... Main article Magnetic monopole A magnetic monopole is a hypothetical particle (or class of particles) that has, as its name suggests, only one magnetic pole (ei ... In other words, it would possess a "magnetic charge" analogous to an electric charge ... Magnetic field lines would start or end on magnetic monopoles, so if they exist, they would give exceptions to the rule that magnetic field lines neither start nor end ...

Famous quotes containing the words field and/or magnetic:

    Mine was, as it were, the connecting link between wild and cultivated fields; as some states are civilized, and others half-civilized, and others savage or barbarous, so my field was, though not in a bad sense, a half-cultivated field. They were beans cheerfully returning to their wild and primitive state that I cultivated, and my hoe played the Ranz des Vaches for them.
    Henry David Thoreau (1817–1862)

    We are in great haste to construct a magnetic telegraph from Maine to Texas; but Maine and Texas, it may be, have nothing important to communicate.
    Henry David Thoreau (1817–1862)