Chapter 27, Problem 39P

(II) A 15-loop circular coil 22 cm in diameter lies in the xy plane. The current in each loop of the coil is 7.6 A clockwise, and an external magnetic field $\stackrel{\to }{B}=\left(0.55\hat{i}+0.60\hat{j}-0.65\hat{k}\right)\text{T}$ passes through the coil. Determine (a) the magnetic moment of the coil, $\stackrel{\to }{\mu }$; (b) the torque on the coil due to the external magnetic field; (c) the potential energy U of the coil in the field (take the same zero for U as we did in our discussion of Fig. 27–22).