what is magnetic field lines

Magnetic field lines are a visual representation of the magnetic field. They form closed loops and describe the direction of the magnetic force on a north monopole at any given position. The density of the lines indicates the strength of the magnetic field, with the field being stronger where the lines are closer together. Magnetic field lines never cross each other, and they are used as a qualitative tool to visualize magnetic forces. They are also used to represent the magnetic field in a mathematical form, making it easier to understand and analyze magnetic phenomena