5.24 A Rowland ring of mean radius 15 cm has 3500 turns of wire wound on a ferromagnetic core of relative permeability 800. What is the magnetic field B in the core for a magnetizing current of 1.2 A?
Mean radius of Rowland ring, r= 15 cm =0.15 m Number of turns on a feromagnetic core, N= 3500 Relative perme ability of the core material, μr=800 Magnetising curent, I=1.2 A The magnetic field is given by the relation: B=μrμ0IN2πr Where,μ0=Permeabilityoffreespace=4π×10-7TmA-1 B=800×4π×10-7×1.2×35002π×0.15=4.48T Therefore, the magnetic field in the core is 4.48 T.