Final answer:
Magnetic field lines exit a magnet from the north pole and enter through the south pole, indicating the direction of the magnetic field. The density of these lines reflects the strength of the magnetic field, which decreases with distance from the magnet.
Step-by-step explanation:
The magnetic field lines of a magnet spread out from the north pole and re-enter the magnet at the south pole. This is because the direction of the magnetic field is defined as the direction in which the north pole of a compass needle points. When placed near the north pole of a magnet, the north pole of a compass needle is repelled and will point away from the north pole of the magnet. Conversely, if placed near the south pole of the magnet, the compass needle's north pole is attracted and will point towards the south pole.
It is important to remember that magnetic field lines are continuous loops, as depicted in the provided figures. The density of these lines, or how close they are to each other, indicates the strength of the magnetic field: closer lines denote a stronger field. As such, contrary to the electric field lines of a pair of equal and opposite charges, the magnetic field lines form closed loops, where they exit the north pole and enter the south pole, continuing through the magnet back to the north pole.
When it comes to experience with magnets, one can note that the magnetic field strength does indeed decrease with distance, as suggested by the field lines spreading out as they move away from the poles. This is consistent with our observations when using magnets, where the force of attraction or repulsion decreases as the magnets move further apart.