Chapter 27, Problem 27.77P

A circular loop of wire with area A lies in the xy-plane. As viewed along the z-axis looking in the −z-direction toward the origin, a current I is circulating clockwise around the loop. The torque produced by an external magnetic field $\stackrel{\to }{\text{B}}$ is given by $\stackrel{\to }{\tau }$ = D(4î − 3ĵ), where D is a positive constant, and for this orientation of the loop the magnetic potential energy U = − $\stackrel{\to }{\mu }$ • $\stackrel{\to }{\text{B}}$ is negative. The magnitude of the magnetic field is B₀ = 13D/IA. (a) Determine the vector magnetic moment of the current loop. (b) Determine the components B_x, B_y and B_z. of $\stackrel{\to }{B}$.