A
magnetic core is a piece of
magnetic material with a high
permeability used to confine and guide
magnetic fields in electrical,
electromechanical and magnetic devices such as
electromagnets,
transformers,
electric motors,
generators,
inductors, magnetic
recording heads, and magnetic assemblies. It is made of
ferromagnetic metal such as iron, or
ferrimagnetic compounds such as
ferrites. The high permeability, relative to the surrounding air, causes the
magnetic field lines to be concentrated in the core material. The magnetic field is often created by a coil of wire around the core that carries a current. The presence of the core can increase the magnetic field of a coil by a factor of several thousand over what it would be without the core.