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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,
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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