Magnetic torque aligns dipole with field

Steps:

• Magnet starts perpendicular to field from U (north) to V (south).
• North pole repelled by U, south attracted to V, creating anticlockwise torque.
• Torque rotates magnet 90° anticlockwise to align with field lines.
• Alignment reaches equilibrium, stopping rotation.

Why B is correct:

• Torque formula τ = μB sinθ drives 90° anticlockwise rotation to θ=0 (stable alignment), then stops.

Why the others are wrong:

• A: Rotation is anticlockwise, not clockwise.
• C: Stops after alignment, no translation toward U.
• D: Wrong rotation direction; no motion toward V.

Final answer: B