The lines drawn in a magnetic field along which north magnetic pole moves, are called magnetic field lines. With the help of a small magnetic compass, the direction of a magnetic field at a point is determined. When the compass is moved along the magnetic line, then the line drawn from the south pole to the north pole indicates the direction of the magnetic field.
The characteristic properties of magnetic field lines are :
(i) The magnetic lines originate from north pole and ends at south pole.
(ii) The magnetic lines do not intersect each other.