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DD: Didaktik der Physik

DD I: HV I

DD I.1: Invited Talk

Monday, March 7, 2005, 14:30–15:30, TU A053

Teaching about Light Interference Constructively — •Gorazd Planinsic — Faculty for Mathematics and Physics, University of Ljubljana, Slovenia

Many students have problems in gaining functional understanding of the formula expressing the conditions of interference maxima in Young’s double-slit experiment. The derivation of the formula is based on a "mysterious" geometrical construction, which distracts students’ attention from the physical content of the phenomenon. A simple demonstration tool that can be used as a mechanical model for Young’s experiment will be presented. The model may help students, missing formal thinking abilities, to construct a functional mental picture of the phenomenon. From here we will continue to the multiple slit interference and then to the light interference on a compact disk. A simple analysis of what happens to the light that enters the CD will lead us to surprising predictions. Using simple experiments we will verify these predictions and finally complete the story about the interference on a CD.