What are field lines?
The magnetic force on the north and south poles of a magnet is illustrated by the field lines of the magnetic flux force. Field lines point in the direction of the north pole of a freely rotating compass needle. They can be visualized with the help of iron filings, forming chains along magnetic field lines as "arrows" pointing from the north to the south pole.
The density and arrangement of the magnetic field lines provide information about the strength and shape of the magnetic field. In a strong magnetic field, the field lines are close together and run in straight lines from the north to the south pole. In a weak magnetic field, the field lines are farther apart and run in curved lines.
Magnetic field lines are often consulted in engineering to study and understand the magnetic field in electric motors, transformers, and other electromagnetic devices.
In physics and electrical engineering, magnetic field lines are often described by the Biot-Savart law and Ampères circuital law, which define how magnetic field lines form and behave due to electric currents and magnetic moments.