Answer: m/2.
- A m/4
- B m/2
- C m
- D 2m
Correct answer: B. m/2
Explanation: Cutting perpendicular to the axis halves the length (and pole strength stays), so each moment is m/2.
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.