A loop ABCDA, carrying current I =12 A, is placed in a plane, consists of two semi-circular segments of radius R_1=6 π m and R_2=4 π m. The magnitude…

A loop ABCDA, carrying current $\displaystyle \mathrm{I}=12 \mathrm{~A}$, is placed in a plane, consists of two semi-circular segments of radius $\displaystyle \mathrm{R}_1=6 \pi \mathrm{~m}$ and $\displaystyle \mathrm{R}_2=4 \pi \mathrm{~m}$. The magnitude of the resultant magnetic field at center O is $\displaystyle \mathrm{k} \times 10^{-7} \mathrm{~T}$. The value of k is $\displaystyle \_\_\_\_$. (Given $\displaystyle \mu_{\mathrm{o}}=4 \pi \times 10^{-7} \mathrm{Tm} \mathrm{A}^{-1}$ )