9. A square coil of side 10 cm consists of 20 turns and carries a current of 12 A. The coil is suspended vertically and the normal to the plane of the coil makes an angle of with the direction of a uniform horizontal magnetic field of magnitude 0.80 T. What is the magnitude of torque experienced by the coil?
The magnitude of torque experienced by a current-carrying coil in a magnetic field is given by
where n = number of turns, I is the current in the coil, A is the area of the coil and is the angle between the magnetic field and the vector normal to the plane of the coil.
In the given question n = 20, B=0.8 T, A=0.10.1=0.01 m2, I=12 A, =30o
=0.96 Nm
The coil therefore experiences a torque of magnitude 0.96 Nm.