Answer: 2:1.
- A 2:1
- B 1:2
- C 1:1
- D 4:1
Correct answer: A. 2:1
Explanation: For a short dipole, the axial field is B<sub>axial</sub> = (μ0/4π)(2m/r³) while the equatorial field is B<sub>equatorial</sub> = (μ0/4π)(m/r³), giving a ratio of 2:1.
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.