EMERGING PHYSICS This page is intentionally left blank EMERGING PHYSICS Avinash W. Joshi Vijay H. Raybagkar Vijayshri Keith V. Desa Rajendra Mahamuni Bhausaheb Shivajirao Bendre Dedicated to Prof. D. P. Khandelwal, Former President, Indian Association to Physics Teachers Copyright © 2009 Dorling Kindersley (India) Pvt. Ltd This book is sold subject to the condition that it shall not, by way of trade or otherwise, be lent, resold, hired out, or otherwise circulated without the publisher’s prior written consent in any form of binding or cover other than that in which it is published and without a similar condition including this condition being imposed on the subsequent purchaser and without limiting the rights under copyright reserved above, no part of this publication may be reproduced, stored in or introduced into a retrieval system, or transmitted in any form or by any means (electronic, mechanical, photocopying, recording or otherwise), without the prior written permission of both the copyright owner and the above-mentioned publisher of this book. ISBN 978-81-317-2936-6 10 9 8 7 6 5 4 3 2 1 Published by Dorling Kindersley (India) Pvt. Ltd, licencees of Pearson Education in South Asia. Head Office: 7th Floor, Knowledge Boulevard, A-8(A), Sector-62, Noida 201309, UP, India. Registered Office: 11 Community Centre, Panchsheel Park, New Delhi 110 017, India. Typeset by Integra Software Solutions Printed in India by Baba Barkha Nath Printers. CONTENTS P REFACE XI A A BOUT THE UTHORS XIII 1 History and Philosophy of Physics 1 1.1 P T 1 HYSICS ODAY 1.2 P P -M E 3 HYSICS IN THE RE ODERN RA 1.2.1 Early Thought 3 1.2.2 Ancient Indian Philosophy 5 1.2.3 Philosophy of the Ancient Greeks 6 1.2.4 Astronomy in the Ancient Times 7 1.2.5 Some Aspects of the Methodology of Ancient Philosophers 8 1.2.6 Zeno’s Paradox 8 1.2.7 The Middle Ages and the Islamic Contribution 8 1.3 T S S C : HE IXTEENTH AND EVENTEENTH ENTURIES R S S R 10 ENAISSANCE IN CIENCE AND THE CIENTIFIC EVOLUTION 1.3.1 The Copernican Revolution 10 1.3.2 Explaining Astronomical Observations: Planetary Orbits 11 1.3.3 Galileo Galilei 12 1.3.4 The Method of Science 15 1.3.5 Isaac Newton and his Contemporaries 17 1.4 P -N C P N OST EWTONIAN LASSICAL HYSICS UP TO THE INETEENTH C 18 ENTURY 1.4.1 Heat 19 1.4.2 Optics 19 1.4.3 Electromagnetism 20 1.4.4 Atomic Structure 22 1.4.5 Mechanics 22 1.5 T W –P S L 23 HE AVE ARTICLE EESAW OF IGHT 1.5.1 Black-Body Radiation 24 1.5.2 Further Evidence for the Particle Model of Light 27 1.6 F C Q M 29 ROM LASSICAL TO UANTUM ECHANICS 1.6.1 The Bohr Atom 29 vi | CONTENTS 1.7 D Q M 33 EVELOPMENT OF UANTUM ECHANICS 1.7.1 Bose and his Statistics 34 1.7.2 Pauli’s Exclusion Principle 34 1.7.3 Uncertainly Principle 35 1.7.4 Relativistic Quantum Mechanics 35 1.8 S O M C T C 36 OME THER AJOR ONTRIBUTIONS IN THE WENTIETH ENTURY 1.8.1 Astronomy 36 1.8.2 Sub-atomic Physics 37 1.8.3 Solid-State Physics and Electronics 37 1.8.4 Extraordinary Contributors 37 1.9 I S 38 NDIAN CIENTISTS 1.9.1 Jagdish Chandra Bose 38 1.9.2 Sir Chandrashekhara Venkata Raman 38 1.9.3 Meghnad Saha 39 1.9.4 Satyendra Nath Bose 40 1.9.5 Subrahmanyan Chandrashekhar 40 1.10 P A 41 HILOSOPHICAL SPECTS 1.10.1 Universal Law of Gravitation 41 1.10.2 Coulomb’s Law 42 1.10.3 Planck’s Law 42 1.10.4 Bohr’s Hydrogen Atom 42 1.10.5 Special Theory of Relativity 42 1.10.6 The Ether Hypothesis 43 1.10.7 The Quantitative Nature of Physics 43 1.10.8 On the Language of Physics 44 1.10.9 The Message 45 2 Lasers and Laser Applications 51 2.1 I 51 NTRODUCTION 2.2 I R W M 51 NTERACTION OF ADIATION ITH ATTER 2.3 E ’ P 55 INSTEIN S REDICTION 2.3.1 Important Features of Stimulated Emission 56 2.4 M S 56 ETASTABLE TATE 2.4.1 Population of Atoms 56 2.4.2 Einstein’s Relations 58 2.4.3 Population Inversion 59 2.4.4 Active Medium 60 | vii CONTENTS 2.5 L P 60 ASER UMPING 2.5.1 Three-level Pumping Scheme 60 2.5.2 Four-level Pumping Scheme 61 2.6 O F 61 PTICAL EEDBACK 2.6.1 The Stable Confi guration 63 2.7 C L 63 HARACTERISTICS OF ASERS 2.8 T L 66 YPES OF ASERS 2.8.1 Ruby Laser 66 2.8.2 Helium–Neon Laser 69 2.9 A L 70 PPLICATIONS OF ASERS 2.9.1 Medicine 71 2.9.2 Optical Communication 72 2.9.3 Defence 72 2.9.4 Mechanical Industry 73 2.9.5 Electronic Industry 74 2.9.6 Consumer Electronic Industry 74 2.9.7 Nuclear Energy 74 2.9.8 Holography 75 2.9.9 Fundamental Research 76 3 Sensors and Transducers 81 3.1 I 81 NTRODUCTION 3.2 E T 81 LECTRICAL RANSDUCERS 3.3 S T 83 ELECTING A RANSDUCER 3.4 T S 83 EMPERATURE ENSORS 3.4.1 Thermocouple 84 3.4.2 Thermocouple Materials 85 3.4.3 Thermistors 87 3.4.4 Platinum Resistance Thermometers 89 3.4.5 IC Temperature Sensors (Integrated Circuit Temperature Sensors) 91 3.4.6 Quartz Thermometer 92 3.4.7 Pyrometers 93 3.5 L S 96 IGHT ENSORS 3.5.1 Vacuum-Type Photocell 97 3.5.2 Gas-Filled Photocell 97 3.5.3 Photomultiplier Tubes 98 3.5.4 Photoconductive Cells (LDRs) 99 3.5.5 Photodiode 100 viii | CONTENTS 3.5.6 Phototransistors 102 3.5.7 Photothyristors 104 3.5.8 Photovoltaic Cells 105 4 Bioelectricity 108 4.1 E O L S 108 LECTRICITY BSERVED IN IVING YSTEMS 4.1.1 Introduction 108 4.2 O B 110 RIGIN OF IOELECTRICITY 4.2.1 Electric Properties of the Biological Membrane 110 4.3 N S F 111 EURON TRUCTURE AND UNCTION 4.3.1 Nervous System 111 4.3.2 Nervous System of Humans 111 4.3.3 Neurons 112 4.4 A A C 113 N XON AS A ABLE 4.5 M R C 113 EMBRANE ESISTANCE AND APACITANCE 4.6 S P T 114 ODIUM AND OTASSIUM RANSPORT 4.7 R P A P 115 ESTING OTENTIAL AND CTION OTENTIAL 4.8 C V 116 ONDUCTION ELOCITY 4.8.1 Ionic Theory of Nerve Impulse 116 4.8.2 Transmission of Nerve Impulse Along the Nerve Fibre 116 4.8.3 Saltatory Conduction of Nerve Impulse 119 4.9 N E 120 ERNST QUATION 4.10 A B 121 PPLICATIONS OF IOELECTRICITY 4.10.1 Electrocardiogram 121 4.10.2 Electroencephalogram 123 4.10.3 Electromyogram 124 4.10.4 Electroretinogram 125 4.10.5 Electrooculograph 125 5 Nanomaterials 130 5.1 I 130 NTRODUCTION 5.1.1 A Brief History of Nanotechnology 131 5.2 N 132 ANOSCIENCE 5.2.1 What is Nanoscience? 132 5.2.2 How Do We Study Nanoscale Objects? 134 5.2.3 Impact of Nanoscience 141 | ix CONTENTS 5.3 Q S E 143 UANTUM IZE FFECT 5.3.1 Quantum Confi nement 143 5.3.2 Particle in a Box 143 5.3.3 Quantum Dot 145 5.3.4 Quantum Wire 145 5.3.5 Modelling of Quantum Size Effect 146 5.4 S I E 147 URFACE AND NTERFACE FFECTS 5.5 W M N S S ? 148 HAT AKES ANOSCIENCE O PECIAL 5.5.1 Optical Properties 148 5.5.2 Electrical Properties 149 5.5.3 Chemical Properties 149 5.5.4 Mechanical Properties 150 5.5.5 Magnetic Properties 151 5.5.6 Melting Temperature 151 5.5.7 Structural Properties 151 5.6 P N M 153 REPARING ANOSCALE ATERIALS 5.6.1 Top-Down Approach 153 5.6.2 Bottom-Up Approach 154 5.6.3 Chemical Methods 154 5.6.4 Physical Methods 155 5.7 B (B N ) 155 IOMIMICKING IOLOGICAL ANOMATERIALS 5.7.1 Microelectromechanical System 156 5.7.2 Nanoelectromechanical Systems 156 5.8 C —A S M 157 ARBON PECIAL ATERIAL 5.8.1 Nanoscale Miracles 157 5.9 N 158 ANOETHICS 5.9.1 The Good Things About Nanotechnology 158 5.9.2 The Bad Things About Nanotechnology 159 A 163 PPENDIX I 165 NDEX