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Permanent Magnets, Magnetic F ield B, and the Relationship between Current and B. By Joseph Turley a nd Michael Marrero. Permanent magnets. A permanent magnet is an object that retains its magnetism after being removed from an external field. Remanence and coercitivity.
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Permanent Magnets, Magnetic Field B, and the Relationship between Current and B. By Joseph Turley and Michael Marrero
Permanent magnets • A permanent magnet is an object that retains its magnetism after being removed from an external field.
Remanence and coercitivity • Remanence is the amount of magnetization left after the magnet is removed from a magnetic field. • Coercitivity is the amount of mgnetivity to revert the magnet to a state of zero magnetization.
Magnetic field • Magnetic field is the mathematical description of the relationship between magnetic influence and electric current. • Magnetic fields are produced by the movement of electric charges.
Units associated with magnetic fields • The Tesla is the unit associated with magnetic fields • 1 Tesla is equal to 1 Ns/Cm. • For smaller magnetic fields they use Gauss • 1 Tesla = 10,000 Gauss
Relationship between Magnetic field and Current • All moving charges produce a magnetic field. • Magnetic field lines are made of concentric circles. • More current means greater magnetic field.
Concept question • What happens when a ferromagnetic material is magnetized with a magnetic field pointed in the opposite direction of which it was magnetized originally?
Concept question • Given all other things equal, which would have the greater magnetic field – A wire with a current of 10 amperes running through it? Or a wire with 20 Amperes of current running through it?