Once the potential is computed, the electric fields can easily be computed via:the equation shown below.
<math> \mathbf{E(\vec r)} = - \nabla \varphi(\vec r)</math>
EM.Ferma can also compute magnetic fields from simple line sources via the Biot-Savart Law:
<math> \mathbf{B} = \frac{\mu_0}{4\pi}\int_C \frac{I d\mathbf{l} \times \mathbf{\hat r}}{|\mathbf{r}|^2}</math>