Answer: 6 × 10-3.
- A 1.5 × 10-3
- B 3 × 10-3
- C 6 × 10-3
- D 9 × 10-3
Correct answer: C. 6 × 10-3
Explanation: Curie's law: χ is inversely proportional to T. Halving T from 300 K to 150 K doubles χ to 6 × 10-3.
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.