Chapter 8: Problem 6
Show that the differential work in moving a current element \(I d \mathbf{L}\) through a distance \(d \mathbf{l}\) in a magetic field \(\mathbf{B}\) is the negative of that done in moving the element \(I d \mathbf{l}\) through a distance \(d \mathbf{L}\) in the same field.