Answer: parallel to.
- A parallel to
- B antiparallel to
- C perpendicular to
- D at 45° to
Correct answer: A. parallel to
Explanation: U = −mB cosθ is minimum (most negative) at θ = 0°, i.e. parallel alignment.
Magnetic field lines form closed loops: outside the bar magnet they run from the N pole to the S pole; inside, they continue from S back to N, so the lines never start or end anywhere.
Concept context
Bar magnets, Earth's magnetism, and how different materials respond to an external magnetic field - diamagnetic, paramagnetic, and ferromagnetic behaviour.