A small square loop of wire of side l is placed inside a large square loop of wire L ( L ≫ l). Both loops are coplanar and their centres coincide at…

A small square loop of wire of side $\displaystyle l$ is placed inside a large square loop of wire $\displaystyle \mathrm{L}(\mathrm{L} \gg l)$. Both loops are coplanar and their centres coincide at point O as shown in figure. The mutual inductance of the system is :