The relative magnetic permeability of a magnetic material is $800$. Identify the nature of magnetic material and state its own properties.

(a) An iron ring of relative permeability ${\mu }_r$ has windings of insulated copper wire of $n$ turns per metre. When the current in the windings is $I$, find the expression for the magnetic field in the ring.
(b) The susceptibility of a magnetic material is $0.9853$. Identify the type of magnetic material. Draw the modification of the field pattern on keeping a piece of this material in a uniform magnetic field.