Explain hard ferromagnetic and soft ferromagnetic materials.

(N/A) Hard ferromagnetic materials: In some ferromagnetic materials,the magnetization persists even after the removal of the external magnetic field. Such materials are called hard magnetic materials.
Alnico,an alloy of iron,aluminum,nickel,cobalt,and copper,is one such material. Naturally occurring lodestone is also a hard ferromagnetic material. Its relative permeability is $> 1000$.
Such materials are used to form permanent magnets,for example,in compass needles.
Soft ferromagnetic materials: There are some ferromagnetic materials in which the magnetization disappears upon the removal of the external magnetic field. These materials are called soft magnetic materials.
These materials are used in electric bells,cranes,transformers,etc.