(a) An iron ring of relative permeability μr 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.
(a) :Copper wire windings on the iron ring forms a toroid.
Magnetic field due to a toroid is given by B=μnI
where μ is the permeability of the medium, n is the number of turns per unit length and I is the current flowing.
Also, μ=μrμo
⟹ B=μrμonI
(b) : Susceptibility of the magnetic material is given as χ=0.9853
Since the magnetic susceptibility of paramagnetic material is positive. So the given substance must be a paramagnetic material.