An insulated wire is wound so that it forms a flat coil with N=200 turns. The radius of the innermost turn is r_1=3 cm, and of the outermost turn…

An insulated wire is wound so that it forms a flat coil with $\displaystyle N=200$ turns. The radius of the innermost turn is $\displaystyle r_1=3 \mathrm{~cm}$, and of the outermost turn $\displaystyle r_2=6 \mathrm{~cm}$. If $\displaystyle 20$ mA current flows in it then the magnetic moment will be $\displaystyle \alpha \times 10^{-2} \mathrm{~A} . \mathrm{m}^2$. The value of $\displaystyle \alpha$ is $\displaystyle \_\_\_\_$.