A square coil of 50 turns and side 0.10m is free to rotate about a vertical axis through its centre. The coil carries a current of 2.0A and is placed in a horizontal uniform magnetic field of 0.30T. It is attached to a torsion spring that exerts a restoring torque of 5.0×10−3N m per degree of twist. Find the steady angular deflection of the coil from its zero-torque position.
a) 60∘
b) 30∘
c) 45∘
d) 15∘