Problem 3.346

Find the interaction energy of two loops carrying currents $I_{1}$ and $I_{2}$ if both loops are shaped as circles of radii $a$ and $b$ , with $a \ll b$ . The loops' centres are located at the same point and their planes form an angle $\theta$ between them.

W_{12}=\frac{\mu_{0} \pi a^{2}}{2 b} I_{1} I_{2} \cos \theta

Electromagnetic Induction. Maxwells Equations