Following is square shape loop, whose one arm BC produces magnetic field B at the centre of coil. The resultant magnetic field due to all the arms will be :-

Magnetic Field due to Circular Coil

Magnetic Field due to Circular Coil

A current carrying wire is bent into the shape of a square coil. The magnetic field produced at the entre of coil by one arm BC is B. Then the resultant magnetic field at the centre due to all the arms will be-

A square loop of side a carris a current I . The magnetic field at the centre of the loop is

A square loop of side a carris a current I . The magnetic field at the centre of the loop is

A square loop of edge 'a' carries a current l. The magnetic field at the centre of loop is