What are magnetic field lines. List two important properties of magnetic field lines.

Magnetic field lines are the lines that emerge from the north pole and merge at the south pole. Two important properties of magnetic field lines are: (1) The relative strength of the magnetic field is shown by the degree of closeness of the field lines. The field is stronger, that is, the force acting on the pole of another magnet placed is greater where the field lines are crowded. (2) No two field-lines are found to cross each other. If they did, it would mean that at the point of intersection, the compass needle would point towards two directions, which is not possible.