Practice question

**Potential energy of magnetic dipole** U = -m B cosθ explains stability. Given m = 0.9 A·m², B = 0.5 T, θ = 90°, sin90° = 1, τ = 0.45 N·m. For 60°, sin60° = √3/2 ≈0.866, reducing torque proportionally. tau = m B sinθ . Given: m = 0.9 A m² , B = 0.5 T , θ = 90° , sin 90° = 1 . tau = 0.9 × 0.5 × 1 = 0.45 N m . Substituting values gives 0.45 N m, which matches expected magnitude for this magnetic configuration, confirming dipole field dependence on m/r³ and torque relation τ = m B sinθ.