Answer: 0.05 N·m.
- A 0.05 N·m
- B 0.1 N·m
- C 0.025 N·m
- D 0.087 N·m
Correct answer: A. 0.05 N·m
Explanation: Torque τ = mB sin(θ) = 0.5 × 0.2 × sin(30°) = 0.1 × 0.5 = 0.05 N·m.
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.