Reactance is an unpleasant motivational reaction to offers, persons, rules, or regulations that threaten or eliminate specific behavioral freedoms. Reactance occurs when an individual feels that an agent is attempting to limit one's choice of response and/or range of alternatives.

In electrical engineering, the armature is the winding (or set of windings) of an electric machine which carries alternating current.Stephen D.

(a.) A mass or piece of iron or steel, or a collection of pieces of iron designed to be acted on by a magnet. While nickel or cobalt might be used, they rarely or never are except in experimental apparatus. The armature of a permanent horse shoe magnet is simply a little bar of soft iron. When the magnet is not in use it is kept in contact with the poles with the idea of retaining its magnetism. It is then said to be used as a keeper. A bar magnet does not generally have an armature. The armature is also used to exhibit the attraction of the magnet. Sometimes an armature is made of steel and is permanently magnetized. Such an armature, termed a polarized armature, is repelled when its like poles are opposed to like poles of the magnet and otherwise is attracted with force due to the sums of the magnetism. If the magnet is sufficiently powerful depolarization of the armature may ensue when like poles are opposed to like poles. Polarized armatures are used in various appliances, magneto generators, telegraphic instruments and others. (b) In a dynamo or Motor the mass of laminated iron or of wire which carries the coils of insulated wires which are caused to rotate in the field of force of the field magnets in order to establish and maintain potential difference with its accompanying current, or which rotates under the effects of a current in a motor. (See Dynamo Electric Generator.) The work of the armature core is twofold. It acts as a portion of the magnetic circuit, conducting the lines of force, and by virtue of its high permeability or multiplying power concentrating a number of the lines of force through its own substance. To enable it to act with efficiency in this direction it should be made of iron of the highest permeability, and should approach as closely as possible to the armature cores consistent with leaving space for the wire winding. It next acts as a support for the wires which are to be swept through the field of force. Thus it acts both to establish a strong field and then acts as a carrier for the wires which are to be cut by the wires in question. In connection with this subject the different definitions under Armature, Dynamo, Commutator, Induction and similar topics may be consulted. (c) See Armature of Influence Machine. (d) See Armature of Leyden Jar or Static Condenser.

Foster's reactance theorem is an important theorem in the fields of electrical network analysis and synthesis. The theorem states that the reactance of a passive, lossless two-terminal (one-port) network always strictly monotonically increases with frequency.

An armature is the name of the kinematic chains used in computer animation to simulate the motions of virtual human or animal characters. In the context of animation, the inverse kinematics of the armature is the most relevant computational algorithm.

In electrical engineering, current limiting reactors can reduce short-circuit currents, which result from plant expansions and power source additions, to levels that can be adequately handled by existing distribution equipment.