Question

Why are magnetic field lines closed curves?

Answer 1

Magnetic field lines:

1. The imagined path that an isolated north pole would take if it has been allowed to do so are magnetic field lines.
2. Because there are no monopolies in magnets, magnetic field lines are closed curves. A magnet always contains two poles (north pole and south pole), regardless of where it is sliced.
3. Outside the magnet, magnetic field lines begin at the north pole and end at the south pole, while magnetic field lines inside the magnet run south to north. Magnetic field lines form closed loops as a result.