Since 2021, the Selective High School Placement Test has followed a new format. The Thinking Skills section replaces the old General Ability section, with a focus on higher-order thinking skills…
Ideas To Implementation is often the third topic taught by school teachers. Whilst it may be no more difficult than the previous topics, students can often struggle to grasp some of the concepts that are at the core of its theme. Ideas To Implementation looks at how scientists in the past have changed their perspective on certain phenomena and how this has resulted in a wave of new technologies that revolutionised our world, many of which we now very much take for granted.
Much of the syllabus focuses on our reconceptualisation of light, in other words, how once upon a time physicists understood visible light to be a unique form of wave and how now, following major leaps in knowledge, physicists understand visible light as only a portion of a whole spectrum of electromagnetic radiation (EMR) which includes things like radio waves, infrared and gammarays, all of which we now use for various communication and medical technologies. Another part of the reconceptualisation of light was physicists beginning to see light less as a wave but rather a stream of energy bundles or particles often called quanta or photons. Each photon has more or less energy depending on the frequency of light it belongs to. For example, gamma rays have photons with much more energy than infrared photons.
The discovery of light as particles is attributed to the German physicist Max Planck who used his theory to explain the mystery of black body radiation. However, it was picked up and further developed by the other famous German physicist Albert Einstein who showed us how frequency is related to photo energy and helped explain the long observed but never explained Photoelectric Effect. This new understanding of light helped scientists develop integral technologies such a solar cells used in solar panels. However, this is where students can get confused. Is light a wave or is it a particle? With the understanding of physics so far taught at school, surely it has to be one or the other. Rather confusingly it doesn’t! Light is a complicated phenomenon which can be seen as either a wave or particle depending on what else scientists want to find out.
This sort of ambiguity exists in another place in syllabus, this time to do with a special type of material called the semi-conductor. Students learn that semi-conductors are neither conductors nor insulators, but rather somewhere in between. Scientists create them by doping Group IV elements with either Group III or Group V elements. In a normal state they are insulators, but with a little added energy they can become conductive. Semi-conductors are used in all sorts of technologies but most importantly in transistors which are electrical components necessary for the function of the modern radio and the most basic of microprocessors!