Two conducting circular loops \( A \) and \( B \) are placed in the same plane with their centres coinciding as shown in figure. The mutual inductance between them is:
\( \frac{\mu_{0}\pi a^{2}}{2b} \)
\( \frac{\mu_{0}}{2\pi}\cdot\frac{a^{2}}{b} \)
\( \frac{\mu_{0}\pi b^{2}}{2a} \)
\( \frac{\mu_{0}}{2\pi}\cdot\frac{b^{2}}{a} \)