Question

A bar magnet of magnetic moment 4 is aligned at 60 degree with a uniform external magnetic field of 0.60 calculate the work done in turning the magnetic to align its magnetic normal first to the magnetic field second opposite to the magnetic field b the torque on a marketing in the final orientation in second case

Answer 1

6 J/T

Q1 = 60º             Q2 = 90º

B = 0.44T

W = MB(cosQ1 -  cosQ2)

    = 6 x 0.44(cos60º - cos90º)

    = 6 x 0.44 x ½

    = 1.32 J