Q27. A circular coil having 200 turns, $2.5 \times 10 ^ { - 4 } \mathrm {~m} ^ { 2 }$ area and carrying $100 \mu \mathrm {~A}$ current is placed in a uniform magnetic field of 1T. Initially the magnetic dipole moment $( \vec { M } )$ was directed along $\vec { B }$. Amount of work, required to rotate the coil through $90 ^ { \circ }$ from its initial orientation such that $\vec { M }$ becomes perpendicular to $\vec { B }$, is\\
$\_\_\_\_$ $\mu \mathrm { J }$.