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
Famous quotes containing the words magnetic and/or field:
“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 (18171862)
“Every woman who visited the Fair made it the center of her orbit. Here was a structure designed by a woman, decorated by women, managed by women, filled with the work of women. Thousands discovered women were not only doing something, but had been working seriously for many generations ... [ellipsis in source] Many of the exhibits were admirable, but if others failed to satisfy experts, what of it?”
—Kate Field (18381908)