4 WJEC AS Level Physics the physics course. The solutions to these exercises as well as the self-test questions are to be found at the end of the book. Unless the question asks for the reasoning or working, the solutions to mathematical questions are generally limited to a final answer rather than showing the way of reaching the answer. Examination style questions At the end of each of units 1 and 2, you will find a set of examination-style questions. As the style and level of demand of the new AS and A level examinations have changed significantly, these questions are not past-paper questions but have been specially written to reflect the changed demands. Similarly to the exercises at the ends of the sections, parts of these questions have also been written with A level candidates in mind and some parts draw together material from different sections of the specification. The solutions to these questions take the form of model answers and which, in many cases, more than provide the minimum answer to achieve full marks. In some cases alternative, equally valid, answers are given. Margin features The text is supplemented by a number of margin features: Terms & definitions These are physics terms and laws that you need to be able to quote without further information. For example: Physics examination papers always contain a few marks for defining terms or stating a physical law. Study point Some ideas from the main text are further developed in Study points. These are used for material which is important for you to understand but is tangential to the flow of the text. Some Study point boxes include material designed to extend your understanding beyond the requirements of the specification. For example: How to use this book This book has been written to support the WJEC AS Physics specification and the first half of the A level specification. The layout of the book matches that of units 1 and 2 respectively of the AS Physics specification. The same material is specified for units 1 and 2 of the A level. It provides you with information which covers the content requirements of the course as well as plenty of practice questions to allow you to keep track of your progress and to prepare successfully for your AS and A level examinations. This book covers all three of the Assessment Objectives (AOs) required for your WJEC course. The AOs are: • AO1, Knowledge and understanding of physics ideas and practice. This comprises 35% of the AS examination (30% of the A level) including the specified practical activities. • AO2, Applying knowledge and understanding of physics ideas and practice, which comprises 45% of both the AS and A level examinations. • AO3, Analysing, interpreting and evaluating scientific information, ideas and evidence which is 20% of the AS examination (25% of the A level). The main chapters in the book are the AS units 1 and 2. • Unit 1 covers Motion, Energy and Matter • Unit 2 covers Electricity and Light Additional chapters are • Chapter 3 – Practical skills • Chapter 4 – Mathematical skills The unit 1 and 2 sections include much practical and mathematical material in context. Chapters 3 and 4 cover aspects of these skills which are more appropriately dealt with separately. Level of coverage This book contains material which is examined at both AS and A level. It is expected that, whilst some users will take AS Physics only, a large percentage of its users will proceed to take the full A level. Because of this, the level of coverage of both the material and some of the practice questions is higher than required for AS. Practice questions As well as the self-test questions in the margin of the main text, each section in units 1 and 2 ends with an exercise of practice questions. As well as containing material relating to the content of the sections, the exercises contain data-analysis questions around the specified practical work for the unit. Some questions also relate to the content of more than one unit: the A level examination requires candidates to answer such synoptic questions, which bring together a range of ideas from The refractive index , n , of a material is defined by n = c v , where v and c are the speeds of light in the material and a vacuum respectively. Terms & definitions Study point The equation V = ER R+r can be interpreted as the pd across the output resistor, R , for a potential divider with input voltage E .