Give the characteristics of magnetic field lines.

(N/A) The properties of magnetic field lines are as follows:
$(i)$ The magnetic field lines of a magnet form continuous closed loops. This is unlike electric field lines,which begin from a positive charge and end on a negative charge or extend to infinity.
$(ii)$ The tangent drawn to a magnetic field line at any given point represents the direction of the net magnetic field $\overrightarrow{B}$ at that point.
$(iii)$ The density of field lines indicates the magnitude of the magnetic field. The larger the number of field lines crossing per unit area,the stronger is the magnitude of the magnetic field $\overrightarrow{B}$.
$(iv)$ Magnetic field lines never intersect each other. If they were to intersect,the tangent at the point of intersection would indicate two different directions for the magnetic field at the same point,which is physically impossible.