Magnetism
Magnetism is a class of physical phenomena that are mediated by magnetic fields. Electric currents and the magnetic moments of elementary particles give rise to a magnetic field, which acts on other currents and magnetic moments. The most familiar effects occur in ferromagnetic materials, which are strongly attracted by magnetic fields and can be magnetized to become permanent magnets, producing magnetic fields themselves. Only a few substances are ferromagnetic; the most common ones are iron, nickel and cobalt and their alloys. The prefix "" refers to iron, because permanent magnetism was first observed in lodestone, a form of natural iron ore called magnetite, FeO.
Magnadur
Magnadur is a sintered barium ferrite, specifically BaFeO in an anisotropic form. It is used for making permanent magnets. The material was invented by Mullard and was used initially particularly for focussing rings on cathode ray tubes. Magnadur magnets retain their magnetism well, and are often used in education. Magnadur can also be used in DC motors.