Physics+-+Light+Modeling

Visible light is a fascinating but elusive concept. On the one hand, we are all very familiar with it. On the other hand, it is difficult to define what light physically is. This summer, I took a three week seminar for which the primary purpose was to create a model to explain what light is. This workshop was a continuation of a workshop I took last summer on modeling mechanics. The premise is that students will better understand concepts in physics if they have a physical model on which they can rely. Modeling is especially useful for helping students grasp abstract concepts in mechanics such as energy and momentum. The nature of light is very abstract and therefore well suited to the modeling approach. The unit on light will begin by asking the students what their definition of light is. The unit consists of several labs that allow students to observe and test various aspects of light (for example, the nature of shadows, laser beams, reflections from mirrors, images through lenses, etc...). Students will periodically be given opportunities to revisit their definition of light based on what they observe and whether what they observe contradicts their initial definition. For example, does the definition of light explain why it bends when passing from air to water or glass? Asking students to repeatedly consider and revise their definition of light will ultimately help them understand it. What is really interesting about light is that it sometimes behaves like an energy wave and sometimes it behaves like a particle. Now there's the rub. That it exhibits these two distinct characteristics makes it all the more difficult to understand. Currently, no textbook treats light with one tidy model. Isaac Newton misunderstood light; Thomas Young half understood it; Einstein developed the most comprehensive definition of it so far. Students are not expected to come up with a single model that completely explains light. It is hoped that this unit will help shed some light on the subject.