Comparing Teaching Approaches About Maxwell’s Displacement Current Ricardo Karam • Debora Coimbra • Maurı ´cio Pietrocola Ó Springer Science+Business Media Dordrecht 2013 Abstract Due to its fundamental role for the consolidation of Maxwell’s equations, the displacement current is one of the most important topics of any introductory course on electromagnetism. Moreover, this episode is widely used by historians and philosophers of science as a case study to investigate several issues (e.g. the theory–experiment relation- ship). Despite the consensus among physics educators concerning the relevance of the topic, there are many possible ways to interpret and justify the need for the displacement current term. With the goal of understanding the didactical transposition of this topic more deeply, we investigate three of its domains: (1) The historical development of Maxwell’s reasoning; (2) Different approaches to justify the term insertion in physics textbooks; and (3) Four lectures devoted to introduce the topic in undergraduate level given by four different professors. By reflecting on the differences between these three domains, sig- nificant evidence for the knowledge transformation caused by the didactization of this episode is provided. The main purpose of this comparative analysis is to assist physics educators in developing an epistemological surveillance regarding the teaching and learning of the displacement current. 1 Introduction Maxwell’s insertion of the displacement current term in Ampe `re’s law is among the greatest achievements of the human mind. It was a crucial step for the prediction of electromagnetic waves that led to the unification of electromagnetism and optics. It can also be seen as a major innovation in physics’ methods, since the term is deduced within a R. Karam (&) Faculty of Education, Physics Education, University of Hamburg, Von-Melle-Park 8, 20146 Hamburg, Germany e-mail: ricardo.karam@uni-hamburg.de; karam@daad-alumni.de D. Coimbra Faculdade de Cie ˆncias Integradas do Pontal, Federal University of Uberla ˆndia, Uberla ˆndia, Brazil M. Pietrocola School of Education, University of Sa ˜o Paulo, Sa ˜o Paulo, Brazil 123 Sci & Educ DOI 10.1007/s11191-013-9624-3