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Textbook of Engineering Physics Textbook of Engineering Physics Dr. P. S. Aithal Director, Srinivas Group of Institutions, Srinivas Integrated Campus, Mukka Mangalore, Karnataka Dr. H. J. Ravindra Assistant Professor in Physics, Srinivas School of Engineering Srinivas Integrated Campus, Mukka Mangalore, Karnataka Copyright © 2011, Authors All rights reserved. No part of this book may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic, mechanical, photocopying, recording or otherwise, without the prior written permission of the publisher. Making copies of this book or any portion thereof for any purpose other than your own is a violation of copyright law. ISBN: 978-93-80408-44-6 First Edition: New Delhi, 2011 Published by ACME LEARNING PRIVATE LIMITED 2/8, Ansari Road, Daryaganj New Delhi-110 002 Printed at: Rajive Book Binding, Delhi-110040 Detailed Contents Preface Acknowledgements About the Authors Chapter 1: Modern Physics 1.1 1.2 1.3 1.4 1.5 1.6 ..... xiii ...... xv .... xvii 1-36 Introduction to Physics Introduction to Blackbody Radiation Spectrum .........1 .........2 1.2.1 1.2.2 1.2.3 1.2.4 1.2.5 ......... 2 ......... 3 ......... 3 ......... 4 ......... 4 Introduction to Modern Physics Blackbody Radiation Blackbody Radiation Spectrum Energy Distribution in Blackbody Radiation Spectrum Laws of Blackbody Radiation Photo-electric Effect .........7 1.3.1 1.3.2 1.3.3 1.3.4 ......... 7 ......... 8 ........ 10 ........ 10 Definition Experimental Study Laws of Photoelectric Effect Einstein’s Photoelectric Equation Compton Effect ....... 11 1.4.1 1.4.2 1.4.3 ........ 12 ........ 12 ........ 14 Definition Expression for Compton Shift Experimental verification of Compton Shift Wave Particle Dualism ....... 16 1.5.1 1.5.2 1.5.3 1.5.4 ........ 16 ........ 16 ........ 17 ........ 18 de-Broglie Hypothesis de-Broglie’s wavelength de-Broglie’s Wavelength-Extension to Electron Particle Davison and Germer Experiment Matter Waves and their Characteristic Properties ....... 20 1.6.1 1.6.2 1.6.3 1.6.4 ........ 20 ........ 22 ........ 22 ........ 23 Phase velocity, Group velocity and Particle velocity Relation between Phase velocity and Group velocity Relation between Group velocity and Particle velocity Expression for de-Broglie wavelength using Group velocity Textbook of Engineering Physics 1.6.5 Relation between Group velocity, Phase velocity and velocity of Light Solved Problems Exercises Chapter 2: Quantum Mechanics 2.1 Introduction 2.2 Heisenberg’s Uncertainty Principle and its Physical Significance 2.2.1 2.2.2 2.2.3 2.2.4 2.2.5 Statement of Heisenberg’s Uncertainty Principle Heisenberg’s Uncertainty Principle applied to Position and Momentum Heisenberg’s Uncertainty Principle applied to Energy and Time Illustration: Heisenberg Microscope Physical Significance ........ 23 ........ 24 ........ 30 37–56 ....... 37 ....... 38 ........ 38 ........ 38 ........ 38 ........ 39 ........ 40 2.3 Application of Uncertainty Principle 2.4 Wave function, Properties and Physical Significance ....... 41 2.4.1 2.4.2 2.4.3 ........ 41 ........ 41 ........ 41 2.3.1 2.5 2.6 2.7 Why Electron cannot be Present Inside the Nucleus? Wave Function Properties of Wave Function Physical Significance ....... 40 ........ 40 Probability Density and Normalization of Wave Function Setting up of a One Dimensional, Time Independent, Schrödinger Wave Equation ....... 41 2.6.1 2.6.2 2.6.3 ........ 41 ........ 42 ........ 43 Schrödinger Wave Equation Derivation Eigen Values and Eigen Function ....... 41 Application of Schrödinger Wave Equation ....... 43 2.7.1 2.7.2 ........ 43 The Particle in a Box of Infinite Depth Energy Eigen Values and Functions of a Particle in a Potential Well of Infinite Depth 2.7.3 Energy Eigen Values for a Free Particle Solved Problems Exercises Chapter 3: Electrical Conductivity in Metals 3.1 Introduction 3.2 Properties of Metals 3.3 Classical Free Electron Theory 3.3.1 3.3.2 vi Free-electron Concept Assumptions of Classical Free-electron Theory ........ 44 ........ 46 ........ 46 ........ 51 57–80 ....... 57 ....... 58 ....... 58 ........ 58 ........ 58 Detailed Contents 3.3.3 3.3.4 3.3.5 3.3.6 3.4 Expression for Drift Velocity Expression for Electrical Conductivity in Metals Effect of Impurity and Temperature on Electrical Resistivity of Metals Failure of Classical Free-electron Theory Quantum Free-electron Theory ....... 62 3.4.1 Assumptions 3.4.2 Fermi-Dirac Statistics 3.4.3 Fermi-energy – Fermi Factor 3.4.4 Density of States 3.4.5 Expression for Electrical Resistivity/Conductivity 3.4.6 Temperature Dependence of Resistivity of Metals 3.4.7 Merits of Quantum Free–electron Theory Solved Problems Exercises ........ 62 ........ 63 ........ 63 ........ 64 ........ 66 ........ 67 ........ 67 ........ 68 ........ 74 Chapter 4: Dielectric and Magnetic Properties of Materials 4.1 Introduction to Dielectric Materials 4.2 Dielectric Constant and Polarization of Dielectric Materials 4.2.1 4.2.2 4.2.3 4.2.4 4.2.5 4.2.6 4.3 4.4 4.5 4.6 4.7 ........ 59 ........ 59 ........ 60 ........ 62 Dielectric Material Polarization of Dielectrics Dielectric Constant Dielectric Susceptibility Polarizability Relation between Dielectric Constant & Polarization 81–106 ....... 81 ....... 82 ........ 82 ........ 82 ........ 83 ........ 83 ........ 83 ........ 83 Types of Polarization ....... 84 4.3.1 4.3.2 4.3.3 4.3.4 4.3.5 ........ 84 ........ 85 ........ 85 ........ 86 ........ 86 Electronic Polarization (Optical polarization) Ionic Polarization Orientational Polarization Space Charge Polarization Frequency and Temperature Dependence of Polarization Equation for Internal fields in Liquids and Solids ....... 87 4.4.1 4.4.2 ........ 87 ........ 87 Internal Fields in Liquids & Solids Expression for One Dimensional Internal Field Classius–Mussoti Equation Frequency dependence of dielectric constant Ferro and Piezo – electricity ....... 90 ....... 91 ....... 91 4.7.1 4.7.2 4.7.3 ........ 91 ........ 92 ........ 92 Ferroelectric Materials Properties of Ferroelectric Materials Piezoelectric Materials vii Textbook of Engineering Physics 4.8 4.9 4.10 4.11 Important Applications of Dielectric Materials Classification of Magnetic Materials ....... 93 ....... 95 4.9.1 4.9.2 4.9.3 Diamagnetic Materials Paramagnetic Materials Ferromagnetic Materials ........ 96 ........ 97 ........ 98 Hysteresis in Ferromagnetic Materials ....... 99 4.10.1 Definition 4.10.2 Explanation of Hysteresis Curve 4.10.3 Hysteresis Loss ........ 99 ........ 99 ...... 100 Soft and Hard Magnetic Materials ..... 100 4.11.1 Hard Magnetic (H.M) Materials 4.11.2 Properties H.M. Materials 4.11.3 Applications of H.M. Materials 4.11.4 Soft Magnetic (S.M) Materials 4.11.5 Properties S.M. Materials 4.11.6 Applications of S.M. Materials Solved Problems Exercises ...... 100 ...... 101 ...... 101 ...... 101 ...... 102 ...... 102 ........ 93 ...... 103 Chapter 5: Lasers 5.1 Introduction 107-138 ..... 107 5.1.1 ...... 108 5.2 5.3 5.4 Characteristics of Laser Principle and Production of Laser ..... 109 5.2.1 5.2.2 5.2.3 5.2.4 5.2.5 5.2.6 5.2.7 ...... 109 ...... 110 ...... 110 ...... 111 ...... 113 ...... 115 ...... 117 Induced Absorption Spontaneous Emission Stimulated Emission Einstein’s Coefficients (expression for energy Density) Requisites of a Laser System Condition for Laser Action Types of Lasers He-Ne Laser ..... 118 5.3.1 5.3.2 5.3.3 5.3.4 ...... 118 ...... 119 ...... 120 ...... 120 Principle Construction Working Applications Semiconductor Laser ..... 120 5.4.1 5.4.2 5.4.3 ...... 120 ...... 121 ...... 122 viii Principle Construction Working Detailed Contents 5.4.4 5.5 5.6 Applications ..... 124 5.5.1 5.5.2 5.5.3 5.5.4 ...... 124 ...... 125 ...... 126 ...... 127 Laser Welding Laser Cutting Laser Drilling Measurement of Atmospheric Pollutants Holography ..... 128 5.6.1 Introduction to Holography 5.6.2 Principle of Holography 5.6.3 Recording of 3-D Images using hologram 5.6.4 Reconstruction of 3-D Images 5.6.5 Selected Applications of Holography. Solved Problems Exercises ...... 128 ...... 128 ...... 129 ...... 129 ..... 130 ...... 131 ...... 133 Chapter 6: Optical Fibers and Superconductivity 6.1 Introduction to Optical Fiber 6.1.1 6.1.2 6.1.3 6.2 6.3 6.4 6.5 6.6 6.7 ...... 123 Applications of Laser Structure of Optical Fiber Principle of Optical Fiber Manufacturing of Optical Fiber 139-175 ..... 139 ...... 140 ...... 143 ...... 144 Types of Optical Fibers ..... 146 6.2.1 6.2.2 ...... 146 ...... 146 Based on Index Based on Modes of Propagation Propagation Mechanism in Optical Fibers ..... 147 6.3.1 6.3.2 6.3.3 ...... 148 ...... 148 ..... 150 Angle of Acceptance Numerical Aperture Fibre Parameter or Normalised Frequency - “V” Attenuation in Fibers Applications of Optical Fibers ..... 151 ..... 153 6.5.1 6.5.2 6.5.3 6.5.4 ..... ..... ..... ..... Fiber Optic Communications Fiber Optic Sensors Other Applications of Optical Fibers Advantages of Optical Fibre Communication 153 154 155 156 Introduction to Superconductivity ..... 157 6.6.1 ..... 158 Temperature Dependence of Resistivity in Superconducting Materials Effect of Magnetic Field ..... 159 6.7.1 6.7.2 6.7.3 ..... 159 ...... 161 ...... 162 Meissner Effect Type I and Type II Superconductors Temperature Dependence of Critical Field ix