An investigation conducted after standard lecture instruction in a sophomore-level modern physics course revealed that many students were unable to interpret the photoelectric experiment in terms of the photon model for light. Findings from this research were used to guide the development of an interactive computer-based tutorial to address the conceptual and reasoning difficulties that were identified. The primary instructional strategy used in the tutorial is the drawing and interpretation of graphs of current versus voltage for the circuit in the experiment.

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We investigated student difficulties in learning quantum mechanics in an upper division quantum course at the University of Maryland. A set of exam questions and interviews has been developed to probe student understandings of the quantum wavefunction. We find that many students are confused about the relation between the wavefunction and the kinetic energy and often appear to interpret the wave function as an energy. They often display a strong "friction-like" model in which the wave function "loses energy" in tunneling through a barrier.

Results from an investigation of student understanding of physical optics indicate that university students who have studied this topic at the introductory level and beyond often cannot account for the pattern produced on a screen when light is incident on a single or double slit. Many do not know whether to apply geometrical or physical optics to a given situation and may inappropriately combine elements of both.