A rectangular coil of area 2.5cm x 1.5cm has 100 turns. When a current of 2mA is passed through it, the deflection is ${30}^0$. The couple per unit twist of the suspended wire is $1.44\times {10}^{-4}{\mathrm{Nmrad}}^{-1}$ the magnetic induction is nearly……………..T (report to nearest integer).