The mean radius of a Rowland ring is 12 cm and it has 3000 turns of wire wound on its ferromagnetic core of relative permeability 500. If the magnetic field inside the core is 5 T, then the magnetizing current is
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A Rowland ring is treated exactly like a toroid. Remember the magnetic field formula \(B=\frac{\mu_0\mu_rNI}{2\pi r}\).