Practice question

**Geomagnetic field** arises from outer core dynamo, field lines emerge near geographic south pole. Understanding D and I allows conversion between geographic and magnetic coordinates, with B_H = B cos(inclination) used in experiments with tangent galvanometer. B = μ₀ μ_r n I , so I = (B/μ₀ μ_r n) . Given: B = 1.5 T , μ_r = 500 , n = 2000 m⁻¹ , μ₀ = 4π × 10⁻⁷ . I = (1.5/4π × 10⁻⁷ × 500 × 2000) = (1.5/1.256 × 10⁰) ≈ 1.194 A ≈ 1.2 A . Substituting values gives 1.2 A, which matches expected magnitude for this magnetic configuration, confirming