The space surrounding a magnet in which magnetic force is exerted is called a magnetic filed. Magnetic field lines are the lines that are drawn at every point indicating the direction in which a north pole would move if placed at that point. Thcy are determined by placing an imaginary hypothetical north pole at that point and finding the direction in which it would move due to the magnetic filed at that point of a compass needle gets deflected when placed ear a magnet due to the magnetic force exerted by the magnet on it. <br> Some important properties of magnetic field lines are: <br> The tangent drawn at any point on the field line indicates the dircction in which a north pole would move if placed at that point <br> The relative strength of the ficld is proportional to the degree of closeness of Ihe lines. The mure elustered they are the stronger thc ficld in the region. <br> The magnetic field lines never intersect This is bccause a pole can move only in zone direction and if the lincs interseet they wourld have to move in two direction aimultaneously which is npossible.