Which statement correctly describes magnetic field lines?

• A. Magnetic field lines never cross and always point from the south pole to the north pole outside the magnet.
• B. Outside a magnet, magnetic field lines emerge from the north pole and enter the south pole, and the lines form continuous closed loops.
• C. Magnetic field lines are straight, parallel lines everywhere around a bar magnet.
• D. Magnetic field lines begin at isolated north magnetic charges and end at isolated south magnetic charges.

Answer: (B)

Verified step by step guidance

1. Recall the fundamental properties of magnetic field lines: they represent the direction and strength of the magnetic field around a magnet.
2. Understand that magnetic field lines form continuous closed loops, meaning they do not start or end abruptly but loop from one pole of the magnet to the other and back through the magnet.
3. Recognize that outside a magnet, magnetic field lines emerge from the north pole and enter the south pole, indicating the direction of the magnetic field in the surrounding space.
4. Note that magnetic monopoles (isolated north or south magnetic charges) do not exist, so magnetic field lines cannot begin or end on isolated magnetic charges.
5. Conclude that magnetic field lines never cross each other, and they are not necessarily straight or parallel everywhere; instead, they curve to form closed loops around the magnet.