Two circular loops A and B of radii r_A and r_B respectively are made from the same uniform wire. The ratio of their moments of inertia about axis passing through thet centres and perpendicular to their planes is${\mathrm{I}}_{\mathrm{B}}/{\mathrm{I}}_{\mathrm{A}}=8,\text{ then }\left({\mathrm{r}}_{\mathrm{B}}/{\mathrm{r}}_{\mathrm{A}}\right)=$