A bar magnet with a magnetic moment 5 . 0 A m 2 is placed in parallel position relative to a magnetic field of 0 . 4 T . The amount of required work done in turning the magnet form parallel to antiparallel position relative to the field direction is ________.

Step-by-step solution

For a bar magnet, the work done in turning from parallel to antiparallel position relative to the field direction is W = M B cos θ 1 - cos θ 2 , here, θ 1 = 0 °   and   θ 1 = 180 ° . W = - M B cos 180 ° - m B cos 0 ° W = 2   M B = 2 × 5 × 0 . 4 = 4   J