Consider two thin identical conducting wires covered with very thin insulating material . One of the wires is bent into a loop and produces magnetic field $\;B_{1}\;$ , at its center when a current I passes through it .The second wire is bent into a coil with three identical loops adjacent to each other and produces magnetic field $\;B_{2}\;$ at the center of the loops when current $\;\large\frac{I}{3}\;$ passes through it . The ratio $\;B_{1} : B_{2}\;$ is :
