13 Metals 13.1 History fo the Use f Metals 13.2 How to Obtain Meatls 13.3 Properties and Uses of Metals 13.4 Making Metals More Useful 13.5 Environmental Problems Associated with the Disposal of Used Metals Summary Glossary Key Points Test youreslf 14 Materials of the Modern World 14.1 Making Plastics from Crude Oil 14.2 Environmental Probems Associated with the Disposal of Plastics 14.3 Composite Materials Summary Glossary Key Points Test yourself 15 Light,Colours and Beyond 15.1 How Do We See an Object? 15.2 Reflection at Plane Surfaces 15.3 Colour 15.4 Beyond the Visible Spectrum 15.5 Beyond Infrared and Ultraviolet 15.6 Refraction and Its Practical Uses 15.7 Optical Fibres and Total lnternal Reflection Summary Glossary Key Points Test youreslf index