#magnetism

• Agonic line — An imaginary line on the Earth's surface (an isogonic line of zero value) connecting points where the magnetic declination is zero; along this line, a compass needle points exactly to true geographic north.
• Non-magnetic — Non-magnetic; possessing no magnetic properties or failing to interact with an external magnetic field. In materials science, it applies to substances with negligible magnetic susceptibility, used in precision instruments or MRI equipment to avoid electromagnetic interference.
• Ampere-turn — A non-SI unit of measurement used to express magnetomotive force or magnetic potential within a magnetic circuit, represented by the symbol At. One ampere-turn equals the magnetomotive force produced by a steady direct current of one ampere flowing through a coil consisting of a single turn.
• Ampère — The surname of the famous French physicist and mathematician André-Marie Ampère (1775–1836), considered one of the primary founders of classical electromagnetism. He discovered the fundamental laws of interaction between electric currents (Ampère's Law) and invented numerous experimental devices; his name was eternalized through the naming of the SI base unit for electric current.
• Ampere-turn — A compact and continuous graphical variant for the compound noun 'amper-spiră'; a unit of measurement used in electrical engineering to express the magnetomotive force or magnetic potential within an inductive circuit, defined as the product of the current intensity in amperes and the number of winding turns.
• Counter-pole — A geographical, geometric, or magnetic point situated in a perfectly opposite and symmetrical position relative to a reference pole on a sphere or celestial body; a structural element defined as the diametrically opposite extremity of the central axis of a physical or mathematical system. In a polar sense, it represents the exact antipode of a geographical pole, such as the South Pole in relation to the North Pole.
• Arago — The reference name of François Arago (1786–1853), a famous French physicist, astronomer, and politician, who made foundational contributions to optics, magnetism, and electromagnetism, demonstrating the wave nature of light. His name became a scientific eponym of major significance, assigned to a lunar crater, a Martian crater, an asteroid, a ring of Neptune, as well as multiple global academic institutions.
• Reinforcement — An assembly of metal parts (steel bars, meshes) embedded in a construction element to increase its tensile or bending strength; the totality of auxiliary devices (valves, cocks) attached to a pipe or boiler for fluid control; the moving metal part of an electromagnetic apparatus or the protective sheath of a cable.
• Astatic — Being in a state of neutral equilibrium, lacking a fixed position of stability, or unaffected by external directive forces such as terrestrial magnetism. In electronics and automatics, it describes a system or regulator that exhibits no steady-state error relative to the reference value, continuing to modify its parameters until the error is completely eliminated.
• Self-excited — Regarding machines, generators, or electrical systems: self-excited; producing its own excitation current required to create its magnetic field without an external power source. Broadly or figuratively, it describes a system, circuit, or state that stimulates, maintains, or amplifies itself through its own internal mechanisms or residual reactions.
• Self-excitation — The phenomenon or process of producing the excitation current required for an electrical generator by the machine itself, utilizing the residual magnetism in the inductor poles. In an abstract or systemic sense, self-excitation represents the property of a dynamic system to generate or intensify physical phenomena, oscillations, or tension states through internal positive feedback.
• Self-induction — An electromagnetic phenomenon consisting of the production of an induced electromotive force within an electric circuit due to the variation of the electric current intensity flowing through that circuit; self-induction. According to Lenz's law, the resulting self-induction current has a direction that opposes the variation of the main current, manifesting as electromagnetic inertia when circuits are established or interrupted.