The research reported in this paper attempted to detect the most frequent difficulties students have in the learning of Ampère's Law, trying to interpret them in the light of Johnson-Laird's mental models theory. Some 230 engineering and mathematics students were researched, during two academic semesters, through their answers to conceptual questions and their written solutions to problems involving Ampère's Law. Research findings clearly show that students solve problems mechanically and provide answers to conceptual questions in the same way. This kind of mechanicism that appear in incomplete or wrong interpretations of the law was object of our analysis.
