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 magnetising current of 1.2 A?
Given data, Rowland ring is toroid with a core of magnetic material, Radius of the ring r=15cm Number of turns of the wire N=3500 Relative permeability of the core,μr=800 Magnetising current, I=1.2A Magnetic field, B=? Using the formula for the magnetic field of a torroid, B=μ0nI Number of turns per unit length, n=2πrN=2π×15×15−23500 Therefore, B=μ0μrnI The magnetic field is given by the relation, B=2πrμrμ0IN =2π×0.15800×4π×10−7×1.2×3500=4.48T
