Practice question

**Relation between B, H, M** is B = μ₀(H+M) = μ₀(1+χ)H. Susceptibility χ = μ_r -1 quantifies material response. Given B, μ_r, n, current I = B/(μ₀ μ_r n), with μ₀ = 4π×10⁻⁷ T·m/A, enabling current calculation for desired B with magnetic core. In a superconductor below its critical temperature, the magnetic field inside becomes zero due to the Meissner effect, where induced currents completely cancel the external field, a hallmark of perfect diamagnetism. Substituting values gives It exhibits perfect diamagnetism, which matches expected magnitude for this magnetic configuration, confirming dipole field dependence on m/r³ and torque relation τ = m B sinθ.