Diffraction phenomenon in optical history and textbooks: Reflections on learning difficulties

Abstract

This paper addresses the difficulties showed by students in the paradigm shift between geometrical optics and wave optics. It tries to interpret its origin at the university level. The research focuses on two aspects: the similarity between the fundamental ideas in the history of science and students conceptions, and the logical development of the issue in textbooks. A historical review of theories about the nature of light is developed analyzing the role of diffraction phenomenon in the paradigm shift. A characterization of the development of optics in major textbooks at university level is then performed, focusing the analysis on the way wave optics is introduced and develop. The results indicate some parallelism between students difficulties and the difficulties experienced by the scientific community in order to accept the wave model. The analysis of textbooks showed that the developmental sequence of topics and some representations used can sometimes reinforce the uncritical use of the ray-model. Finally, it is marked the importance that teachers take into account students difficulties and the interpretations about its origin for the design of educational activities and proposals.