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?


Radius of ring (r) = 15cm = 0.15m

Number of turns in the ring (n) = 3500


Relative permeability of the ferromagnetic core (μr) = 800


Current in the Rowland ring (I) = 1.2A


Magnetic Field due to circular coil (B) =


Where, μ0 = Permeability of free space = 4π × 10-7TmA-1


B = = 4.48T


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