Answer: 0.5 N m.
- A 0.25 N m
- B 0.5 N m
- C 1 N m
- D 2 N m
Correct answer: B. 0.5 N m
Explanation: τ = mB sinθ = 2 × 0.25 × sin90 = 0.5 N m.
Magnetic field of a bar magnet: field lines emerge from the north pole and re-enter at the south pole outside the magnet, forming continuous closed loops. Image: Geek3, CC BY-SA 3.0, via Wikimedia Commons.
Concept context
Bar magnets, Earth's magnetism, and how different materials respond to an external magnetic field - diamagnetic, paramagnetic, and ferromagnetic behaviour.