The invisible magnetic lines that leave the north pole and enter the south pole are called what?

The term used to describe the invisible magnetic lines that emanate from the north pole and return to the south pole is "magnetic field lines." These lines represent the direction and strength of the magnetic field surrounding a magnet. The convention states that the lines originate from the north pole and conclude at the south pole, giving a visual representation of the magnetic influence in surrounding space.

Magnetic field lines are useful for understanding how magnetic forces interact in a given area, showing both the direction of the force (from north to south) and the intensity of the magnetic field (where lines are denser, the field is stronger). This concept is fundamental in fields such as electromagnetism and is critical for understanding how magnets operate, as well as in applications involving electric currents and magnetic fields.

While the term "magnetic flux lines" could seem somewhat synonymous, it is more accurately used in the context of measuring the quantity of magnetic field passing through a defined area, rather than describing the lines themselves. The options related to attraction and repulsion pertain to the interaction of magnets rather than the description of the magnetic lines.