OTERO Maria Rita
congresos y reuniones científicas
Teaching different aspects of light in the unified framework of quantum mechanics
Conferencia; The World Conference on Physics Education 2012; 2012
Institución organizadora:
ABSTRACT: In this paper we address the teaching of different aspects of light in a unified framework and non traditional way, for high school students. Our goal is to show how the quantum theory of light is able to describe different phenomena observed. That is, show the universality of these laws. For this, in a first part, we present a series of experiments showing different characteristics of light. In a second part the laws of quantum mechanics for light are presented and adapted to the mathematical level of high school students. Finally, in a third part, we show how the laws of quantum mechanics describe the observed phenomena. This study is characterized by a careful choice of language used, especially with terms like "photon" or phrases like "particles of light" or "wave-particle duality", that might be confuse for the students in a first stage. The same is noted for the experiments shown and graphic representations used. Specifically, for the first part, i.e. the presentation of experimental results, three experiments are shown. The first one is a beam of light reflected on a mirror, where might be possible to assign the light characteristics associated to particles. The second one is the double slit experiment with light, where the interference pattern formed on the screen exhibits wave-like characteristics. Finally, to questioning the wave or corpuscular character of light, we present a sequence of real images of the interference pattern formation in the double slit experiment, with very low intensity light. The idea is that students notice that there are individual detection events and that the light hits the screen in granular form, a result that could be associated with the impact of "particles". At first, the individual events seem to be distributed randomly over the screen. But as time goes on, an interference pattern of maxima and minima, characteristic of wave behavior, is formed on the screen. In this case the light exhibits a behavior different from previous experiences: some particle-like aspects such as detection of individual events on the screen (which also occurs in the process of light emission by the source), and other wave-like aspects as the interference pattern formed on the screen. We consider that previous sequence is a good teaching strategy to show that it is not possible to associate the light with purely ondulatory or purely corpuscular aspects and therefore we can not reconcile the concept of light completely with everyday concepts of wave or particle.