A circular loop of radius P, carrying current i' lies in x-y plane with its centre at origin The total magnetic flux through x-Y Plane is

The circular loop of radius -R carrying a current i is shown in fig. According to the reciprocitytheorem, the magnetic flux through X-Y plane due to a current i in the ring of radius .R will be equal to the magnetic flux associated with this ring due to current .i in a ring of infinite radius . Obviously, this is zero.