Q27. A coil having 100 turns, area of $5 \times 10 ^ { - 3 } \mathrm {~m} ^ { 2 }$, carrying current of 1 mA is placed in uniform magnetic field of 0.20 T such a way that plane of coil is perpendicular to the magnetic field. The work done in turning the coil through $90 ^ { \circ }$ is $\_\_\_\_$ $\mu \mathrm { J }$.