Problem

A circular loop of wire having a radius of 8.0 cm carries a current of 0.20 A. A vector of unit length and parallel to the dipole moment

\mathbf{M}

of the loop is given by

0.60 \hat{\mathbf{i}} - 0.80 \hat{\mathbf{j}}

. If the loop is located in uniform magnetic field given by

\mathbf{B} = (0.25 \text{ T}) \hat{\mathbf{i}} + (0.30 \text{ T}) \hat{\mathbf{k}}

find, a. the torque on the loop and b. the magnetic potential energy of the loop.