Worked example: Classify and compare: (a) bismuth χ = −1.7 × 10⁻⁴, (b) aluminium χ = +2.2 × 10⁻⁵, (c) soft iron χ ≈ 5000. A 1 T field is applied. Estimate the magnetization M = χH (with H ≈ B/μ0). Step 1: H = B/μ0 = 1/(4π × 10⁻⁷) ≈ 7.96 × 10⁵ A/m. Step 2: (a) M = −1.7 × 10⁻⁴ × 7.96 × 10⁵ ≈ −135 A/m (opposes field — diamagnetic). (b) M = +2.2 × 10⁻⁵ × 7.96 × 10⁵ ≈ +17.5 A/m (weakly with field — paramagnetic). (c) M = 5000 × 7.96 × 10⁵ ≈ 4 × 10⁹ A/m — absurdly beyond iron's saturation (~1.7 × 10⁶ A/m), showing that linear χ fails for ferromagnets: they saturate. Step 3: Lesson — susceptibilities rank the mechanisms across ten orders of magnitude; only the ferromagnet's domains give macroscopic magnetism.