A cell is connected between the points $A \mathrm{ }\mathrm{a}\mathrm{n}\mathrm{d}\mathrm{ }C$ of a circular conductor $ABCD$ with $O$ as centre and angle $AOC=60°.$ If $B_1 \mathrm{a}\mathrm{n}\mathrm{d}\mathrm{ }{B}_2$ are the magnitudes of the magnetic fields at $O$ due to the currents in $ABC \mathrm{a}\mathrm{n}\mathrm{d}\mathrm{ } ADC$ respectively, then ratio $\frac{B_1}{B_2}$ is