Worked example: A bar magnet (M = 2 A·m²) lies on a table. Find B at (a) 20 cm along its axis, (b) 20 cm on its equatorial line. (c) A compass placed at (b) — which way does it point? Step 1: (a) Axial: B = (μ0/4π)(2M/d³) = (10⁻⁷)(2 × 2)/(0.2)³ = (4 × 10⁻⁷)/0.008 = 5 × 10⁻⁵ T = 50 μT, pointing away from the north pole. Step 2: (b) Equatorial: B = (μ0/4π)(M/d³) = (10⁻⁷ × 2)/0.008 = 2.5 × 10⁻⁵ T = 25 μT, pointing toward the magnet's north... precisely: opposite to M, i.e. toward the north pole side? The equatorial field points antiparallel to M (from north to south outside means at the equator it points back toward the magnet's axis, opposite the moment direction). Step 3: (c) Earth's field (~30 μT horizontal) is comparable, so the compass points along the vector sum — neither purely with the magnet nor with Earth. Moral: always account for Earth's field in magnet experiments.