Answer: 90°.
- A 0°
- B 45°
- C 90°
- D 180°
Correct answer: C. 90°
Explanation: Torque = mB sinθ is maximum at θ = 90°.
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.