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). M = chi H . Given: chi = 7 × 10⁻⁴ , H = 3000 A m⁻¹ . M = 7 × 10⁻⁴ × 3000 = 2.1 A m⁻¹ . Substituting values gives 2.1 A m⁻¹, which matches expected magnitude for this magnetic configuration, confirming dipole field dependence on m/r³ and torque relation τ = m B sinθ.