Practice question

**Magnetization M** is magnetic moment per unit volume (A/m), magnetic intensity H = B/μ₀ - M, susceptibility χ = M/H dimensionless, permeability μ = B/H = μ₀(1+χ), relative permeability μ_r = μ/μ₀ = 1+χ. For solenoid with core, B = μ₀ μ_r n I, n turns per meter (m⁻¹), I current (A). Ferromagnetic materials have microscopic domains that align and grow in the presence of an external magnetic field, leading to strong magnetization. This cooperative behavior amplifies the field inside the material significantly. Substituting values gives Ferromagnetic, which matches expected magnitude for this magnetic configuration, confirming dipole field dependence on m/r³ and torque relation τ = m B sinθ.