FE analysis is a useful technique, but the interpretation of the results are sometimes confuse and dark. In this paper we shown some methods to determine the back emf in PMSM and how determine and reduce the cogging torque. Our students use these methods and comparing the obtained results, they learn about the post-processing magnitudes in FE analysis and its interpretation; probably the most difficult task in this calculation method. Additionally these results are compared to a prototype and the results are agreed with the prediction.