A current of 3 A passes through a coil of 100 turns wound around a toriodal core. The core has a mean radius of 0.03 m and a cross-sectional area of 1 cm². The core material has a relative permeability of μ _r  = 2. Permeability of free space is μ ₀ = 4π × 10⁻⁷ H/m. The magnetic field strength produced is 1590 A/m. The magnetic flux within the toroidal core is most nearly