engleski

Identifying student difficulties with atomic spectra

Physics education research is still mostly focused on student understanding of basic topics from classical physics, with less emphasis on topics from modern physics. Examples of such a topic are line spectra. It is important that students develop good understanding of spectra as a prerequisite for understanding of quantum mechanics, as well as astrophysics. The structure and formation of spectra are a part of university and secondary school curricula both in Croatia and in the United States. Systematic investigation of student understanding of atomic spectra was conducted among 1000 science majors in introductory physics courses at University of Zagreb, Croatia and University of Washington, USA. A major focus of the research was on the ability of students to relate the energy levels of an atom to the corresponding discrete line spectrum. Three written questions that probed that ability were constructed, and administered to students after standard instruction on spectra. The results indicate low student understanding of the process of line spectrum formation. Most of the students failed to associate one spectral line with a transition between two energy levels, and tended instead to associate one spectral line with only one energy level. One additional question that probed student understanding of the role of the experimental setup in formation of a line spectrum was constructed and also administered to students. Only between 20 % and 30 % of the students recognized that the type of the light source is critical for the formation of a line spectrum. Identification and analysis of student difficulties guided the design of a set of new instructional materials, tutorials, to supplement instruction in a standard calculus-based physics course. The instructional materials have been validated and proved to be effective at helping students construct and apply a model of spectra formation. Findings from the research questions will be presented, and students’ most frequent conceptual and reasoning difficulties will be discussed. Students’ posttest results and the examples from the tutorial will also be presented and discussed.

physics education research; atomicspectra; university students

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