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 lines form closed loops: outside the bar magnet they run from the N pole to the S pole; inside, they continue from S back to N, so the lines never start or end anywhere.
Concept context
Bar magnets, Earth's magnetism, and how different materials respond to an external magnetic field - diamagnetic, paramagnetic, and ferromagnetic behaviour.