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domain,in physics: see magnetismmagnetism,
force of attraction or repulsion between various substances, especially those made of iron and certain other metals; ultimately it is due to the motion of electric charges.
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Domain (electricity and magnetism)
A region in a solid within which elementary atomic or molecular magnetic or electric moments are uniformly aligned.
Ferromagnetic domains are regions of parallel-aligned magnetic moments. Each domain may be thought of as a tiny magnet pointing in a certain direction. The relatively thin boundary region between two domains is called a domain wall. Within a wall the magnetic moments rotate from the direction of one of the domains to the direction in the adjacent domain.
A ferromagnet generally consists of a large number of domains. For example, a sample of pure iron at room temperature contains many domains whose directions are distributed randomly, making the sample appear to be unmagnetized as a whole. Iron is called magnetically soft since the domain walls move easily if a magnetic field is applied. In a magnetically hard or permanent magnet material a net macroscopic magnetization is introduced by exposure to a large external magnetic field, but thereafter domain walls are difficult to either form or move, and the material retains its overall magnetization.
Antiferromagnetic domains are regions of antiparallel-aligned magnetic moments. They are associated with the presence of grain boundaries, twinning, and other crystal inhomogeneities.
(1) Royal domain, hereditary land possessions of the king in the countries of Western and Central Europe in the Middle Ages. It included ancestral lands, fortresses, cities, forests, and pastures scattered in various areas of the country. It served as a fund for grants of land to the direct vassals of the king and also as the main source for the maintenance of the king and the royal court. The expansion of royal domains through the annexation of estates of large feudal lords was one of the means of strengthening royal power and eliminating feudal fragmentation. Dukes, counts, and other major feudal lords also had their own domains.
(2) Seignorial domain, part of the patrimony (or temporarily held service lands) on which the feudal lord carried on an independent (domanial) economy, using the labor of feudally dependent peasant holders or landless workers. It included arable lands (situated, as a rule, in open fields along with peasant lands), fields, orchards, structures, livestock, and tools and equipment.
in mathematics, an open connected set, that is, a set that satisfies the conditions (1) for any division of the set into two parts, at least one part contains a limit point of the other and (2) for each point in the set, some neighborhood of that point also belongs to the set. Thus, in the plane, the interior of a circle is a domain, but the set of interior points of two externally tangent circles, while open, is not a domain. A domain on a line is an open interval, either finite or infinite (seeINTERVAL AND SEGMENT). There is an infinite variety of domains in the plane. The concept of domain may be extended without change to any topological space.
The Domain Name System maps hostnames to Internet address using a hierarchical namespace where each level in the hierarchy contributes one component to the FQDN. For example, the computer foldoc.doc.ic.ac.uk is in the doc.ic.ac.uk domain, which is in the ic.ac.uk domain, which is in the ac.uk domain, which is in the uk top-level domain.
A domain name can contain up to 67 characters including the dots that separate components. These can be letters, numbers and hyphens.
See domain theory.
domain(1) In a LAN, a subnetwork made up of a group of clients and servers under the control of one security database. Dividing LANs into domains improves performance and security.
(2) In a communications network, all resources under the control of a single computer system.
(3) On the Internet, a registration category. See domain name and Internet domain name.
(4) In database management, all possible values contained in a particular field for every record in the file.
(5) A group of end points (phones or gateways) in a SIP telephony environment. See SIP.
(6) In magnetic storage devices, a group of molecules that makes up one bit.
(7) In a hierarchy, a named group that has control over the groups under it, which may be domains themselves.