Which diagram best illustrates the magnetic field of a bar magnet? A bar magnet with a north and south pole. Field line vectors are leaving the north pole and curl around to the south pole. A bar magnet with a north and south pole. Field line vectors are leaving the south pole and curl around to the north pole. A bar magnet with a north and south pole. Field line vectors are leaving the north pole and curl around to the south pole. A bar magnet with a north and south pole. Field line vectors are leaving the south pole and curl around to the north pole.