5.8 A closely wound solenoid of 2000 turns and area of cross-section , carrying a current of 4.0 A, is suspended through its
centre allowing it to turn in a horizontal plane.
(b) What is the force and torque on the solenoid if a uniform horizontal magnetic field of is set up at an angle of 30° with the axis of the solenoid?
Now,
Magnetic field strength, B =
The angle between the magnetic field and the axis of the solenoid,
Now, As the Magnetic field is uniform, the Force is zero
Also, we know,
= mxB = mBsinθ
= (1.28 )()(sin )
= 4.8 x J
Therefore, Force on the solenoid = 0 and torque on the solenoid = 4.8 x J