A magnetic dipole in a uniform field is in unstable equilibrium when:
**Magnetic dipole in uniform field** experiences torque τ = m B sinθ and potential energy U = -m·B = -m B cosθ, minimum -mB when aligned (θ=0°), maximum +mB at anti-alignment (θ=180°). Work done rotating from θ₁ to θ₂ equals ΔU = mB(cosθ₁ - cosθ₂). The potential energy U = -m B cosθ is maximized when θ = 180° (anti-parallel), making it an unstable equilibrium position. Any small perturbation causes the dipole to rotate toward the stable position ( θ = 0° ), as the energy decreases in that direction. Substituting values gives It is anti-parallel to the field, which matches expected magnitude fo
Ref: NCERT > Physics Book > Magnetism and Matter > Torque on Magnetic Dipole and Potential Energy
