A Flat Rectangular Loop of Wire Is Placed Between the Poles

Multiple Choice

A flat rectangular loop of wire is placed between the poles of a magnet, as shown in the figure. It has dimensions $w = 0.60 \mathrm {~m}$ and $L = 1.0 \mathrm {~m}$ , and carries a current $I = 2.0 \mathrm {~A}$ in the direction shown. The magnetic field due to the magnet is uniform and of magnitude $0.80 \mathrm {~T}$ . The loop rotates in the magnetic field and at one point the plane of the loop is parallel to the field. At that instant, what is the magnitude of the torque acting on the wire due to the magnetic field?

A) $0.96 \mathrm {~N} \cdot \mathrm { m }$
B) $0.48 \mathrm {~N} \cdot \mathrm { m }$
C) $0.40 \mathrm {~N} \cdot \mathrm { m }$
D) $0.83 \mathrm {~N} \cdot \mathrm { m }$
E) $0.00 \mathrm {~N} \cdot \mathrm { m }$