Magnetic Dipole EnergyHardQuestion 20179
Question
Energy of a magnetic dipole of moment m in a field B at angle θ is:
- AmB sinθ
- BmB cosθ
- C−mB cosθCorrect
- DmB tanθ
Correct answer
−mB cosθ
Explanation
U = −m·B = −mB cosθ. Minimum energy (stable equilibrium) at θ = 0 (m parallel to B); maximum (unstable) at θ = 180°.