Student understanding of the wave nature of matter: Diffraction and interference of particles

This paper reports on a study of student understanding of the wave nature o f matter in the context of the pattern produced by the diffraction and inte rference of particles. Students in first-year, second-year, and third-year physics courses were asked to predict and explain how a single change in an experimental setup would affect the pattern produced when electrons or oth er particles are incident on a single slit, double slit, or crystal lattice . The errors made by students after standard instruction indicated the pres ence of similar conceptual and reasoning difficulties at all levels. Among the most serious was an inability to interpret diffraction and interference in terms of a basic wave model. Other errors revealed a lack of a function al understanding of the de Broglie wavelength. Students often treated it as a fixed property of a particle, not as a function of the momentum. An impo rtant goal of this investigation was to provide a research base for the des ign of instruction to help students develop and apply a basic wave model fo r matter. (C) 2000 American Association of Physics Teachers.