Answer: Magnetic field lines.
- A Electric field lines
- B Magnetic field lines
- C Equipotential lines
- D Isobars
Correct answer: B. Magnetic field lines
Explanation: Magnetic field lines are continuous closed curves whose tangent at any point gives the direction of the magnetic field there, and they do not intersect each other.
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.