magnetic flux

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magnetic flux, in physics, term used to describe the total amount of magnetic field in a given region. The term flux was chosen because the power of a magnet seems to "flow" out of the magnet at one pole and return at the other pole in a circulating pattern, as suggested by the patterns formed by iron filings sprinkled on a paper placed over a magnet or a conductor carrying an electric current. These patterns are called lines of induction. Although there is no actual physical flow, the lines of induction suggest the correct mathematical description of magnetism in terms of a field of force. The lines of induction originate on the north pole of the magnet and end on the south pole; their direction at any point is the direction of the magnetic field, and their density (the number of lines passing through a unit area) gives the strength of the field. Near the poles where the lines converge, the field and the force it produces are large; away from the poles where the lines diverge, the field and force are progressively weaker.

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magnetic flux (symbol Φ) Measure in webers (Wb) of the strength and extent of a magnetic field. The flux through an area A at right angles to a uniform magnetic field is Φ = μHA, where μ is the magnetic permeability of the medium and H is the magnetic field intensity. Magnetic flux density, which is measured in teslas (T), is the flux per unit area (symbol B), which equals μH. Change of magnetic flux through a circuit induces an electromotive force.

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magnetic flux The magnetic induction, perpendicular to the surface area of a nearby body, multiplied by the area of the body.