Light


 * Light and electromagnetic radiation.**

The material from 'Protons for Breakfast' is invaluable here because it helps to illustrate perfectly the difference in approach taken to a topic by physics specialists and non-specialists. The power point starts off with relatively familiar phenomena - static on balloons and the like - and builds to a fundamental model of what light actually is. This makes the rest of the explanations about sectra and wave properties far easier to take on board because they form part of a coherent framework. Granted - we know that it takes time and repetition for students to break out of preconceived ideas and to form new models of the universe. However, throughout their physics education, students are going to be taking on new ideas about light. If these do not form part of a coherent framework, then everything that they learn about light is going to be a source of confusion and conflict. Children, especially younger children "... pay attention to what they perceive through their senses rather than the logic, which may suggest a different interpretation..." and " They may hold on to earlier ideas even though contrary evidence is available because they have no access to an alternative view that makes sense to them. In such cases they may adjust their ideas to fit new evidence rather than give it up" (Harlen, 2000 A . p54) Key to those statements is the provision of an alternate framework that makes sense - starting with familiar concepts and building on them in a non-alienating way; I think that the PfB material does that remarkably well.

One of the ways that you can help your students to develop a coherent model in physics is to be conscious of the points in topics where students start to lose sight of the wood for the trees - this is the time to quickly run over basic concepts and reinforce learning - don't be afraid to allude to areas of physics that your students won't need for the exam - it really helps to develop a 'continuum' feel to subjects so that students know where the knowledge leads, just be clear about what they need to know from a particular lesson. This will be particularly important in addressing the wave properties of light. The approach that we took explains colour quite well and may provide a better way for students to look at the behaviour of coloured objects under coloured light. This is a great phenomenogical approach to engaging interest - if you get the right colours and strong enough cloured light, the results are dramatic.

As well as the theory, we looked at shadows, very easy to experiment with and great for looking at light travelling in straight lines and examining which variables are being changed. We took a look at pinhole photography, there are loads of great web resources on this, such as pinhole resource, some good how-to stuff on pinholephotography.com and a slightly less obsessive approach from Kodak. PInhole cameras are great for introducing the idea of ray diagrams; in addition you can make "shortsighted' pinhole cameras as a model of the eye to look at how glasses help the myopic and long-sighted. Pinhole photography is one of those things that might ignite interest in creative learners. From ray diagrams, we get on to image formation, the eye, mirrors and Pepper's Ghost - the film clip in the PP is a nice one to use and also has some interesting themes on the way that scientific phenomna can be misrepresented or abused for entertainment.

Cool little spectroscope that you can make with black paper and an old CD Presentation from the day. The 'Protons for Breakfast' presentation that I nicked so many slides from.

Some useful slides on lenses and telescopes, including some ray diagrams. Optical instrumnents Optical instruments for A2 Galilean telescopes (massively detailed).