Similarly if we consider the field/flux lines of a current carrying conductor as shown in Fig. 4.7 (b), we find that these lines are closed lines, that is, if we consider a closed surface, the number of flux lines that would leave the surface would be same as the number of flux lines that would enter the surface.

From our discussions above, it is evident that for magnetic field,

......................................(4.19)

which is the Gauss's law for the magnetic field.

By applying divergence theorem, we can write:

Hence,                                        ......................................(4.20)       

which is the Gauss's law for the magnetic field in point form.