Fundamentals of Electrical and Electronics Engineering 2021 PDF

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Copyright © Reserved ISBN: 978-93-91505-59-2 No part of this publication may be Book Code: DIP228EN reproduced, stored in a retrieval system or transmitted, in any form or by any means, Fundamentals of Electrical and electronic, mechanical, photocopying, recording or otherwise without prior Electronics Engineering by permission of the publisher. Susan S. Mathew, Saji T. Chacko [English Edition] This book is sold subject to the condition that it shall not, by way of trade, be lent, re-sold, hired out or otherwise disposed First Edition: 2021 of without the publisher’s consent, in any form of binding or cover other than that in Published by: which it is published. Khanna Book Publishing Co. (P) Ltd. Visit us at: www.khannabooks.com Disclaimer: The website links provided by Write us at: [email protected] the author in this book are placed for CIN: U22110DL1998PTC095547 informational, educational & reference purpose only. The Publisher do not endorse these website links or the views of To view complete list of books, the speaker/ content of the said weblinks. Please scan the QR Code: In case of any dispute, all legal matters KPH to be settled under Delhi Jurisdiction only. Printed in India. Acknowledgement T he author(s) are grateful to AICTE for their meticulous planning and execution to publish the technical book for Diploma students. We sincerely acknowledge the valuable contributions of the reviewer of the book Prof. Akole Kishor Pralhad, for making it students’ friendly and giving a better shape in an artistic manner. This book is an outcome of various suggestions of AICTE members, experts and authors who shared their opinion and thoughts to further develop the engineering education in our country. It is also with great honour that we state that this book is aligned to the AICTE Model Curriculum and in line with the guidelines of National Education Policy (NEP) -2020. Towards promoting education in regional languages, this book is being translated in scheduled Indian regional languages. Acknowledgements are due to the contributors and different workers in this field whose published books, review articles, papers, photographs, footnotes, references and other valuable information enriched us at the time of writing the book. Finally, we like to express our sincere thanks to the publishing house, M/s. Khanna Book Publishing Company Private Limited, New Delhi, whose entire team was always ready to cooperate on all the aspects of publishing to make it a wonderful experience. Susan S. Mathew & Saji T. Chacko (v) Preface The book entitled “Fundamentals of Electrical and Electronics Engineering” is an outcome of the rich experience of our teaching of Basic Electrical and Electronics Engineering courses. The initiation of writing this book is to expose to the students of polytechnic, the fundamentals of Electrical and Electronics Engineering as well as enable them to get an insight of the course and develop related practical outcomes. Keeping in mind the purpose of wide coverage as well as to provide essential supplementary information, we have included the topics recommended by AICTE, in a very systematic and orderly manner throughout the book. Efforts have been made to explain the fundamental concepts of the course in the simplest possible way. During the process of preparation of the manuscript, we have considered the various standard text books and accordingly we have developed sections like critical questions, solved and supplementary problems etc. While preparing the different sections emphasis has also been laid on definitions and laws and also on comprehensive synopsis of formulae for a quick revision of the basic principles. The book covers all types of medium and advanced level problems and these have been presented in a very logical and systematic manner. The gradations of those problems have been tested over many years of teaching a wide variety of students. Apart from illustrations and examples as required, we have enriched the book with numerous solved problems in every unit for proper understanding of the related topics. It is important to note that in all the books, we have included the relevant laboratory practical. In addition, besides some essential information for the users under the heading “Know More” we have clarified some essential basic information in the appendix and annexure section. As far as the present book is concerned, “Fundamentals of Electrical and Electronics Engineering ” is meant to prepare students to apply the knowledge of to tackle the challenges and address the related aroused questions that students and diploma holders will face ahead. The course contents are presented in a constructive manner so that an Engineering diploma will prepare the students to work in different sectors. We sincerely hope that the book will inspire the students to understand the concepts and will surely contribute to the development of a solid foundation of the course. Although all care has been taken to check for mistakes and misprints in this text book and laboratory manual, yet it is impossible to claim perfection especially as this is the first edition. Any such errors, mistakes, omissions, suggestions for improvement are highly welcome and can be brought to our notice, which will contribute to the improvement of the future editions of the book. It was indeed a big pleasure to work on different aspects culminating in the form of this book and we do hope that it will be helpful to understand the basic concepts of the vast and interesting field of Electrical and Electronics Engineering and will be a useful learning aid to develop the expected learning outcomes. Susan S. Mathew Saji T. Chacko (vii) Outcome Based Education Outcome based education comprises of outcome based curriculum, outcome based teaching-learning process and outcome based assessment to achieve targeted learning outcomes. As per National Board of Accreditation, after completion of diploma program in engineering and technology the graduate will be able to: PO1. Basic and Discipline specific knowledge: Apply knowledge of basic mathematics, science and engineering fundamentals and engineering specialization to solve the engineering problems. PO2. Problem analysis: Identify and analyse well-defined engineering problems using codified standard methods. PO3. Design/ development of solutions: Design solutions for well-defined technical problems and assist with the design of sys tems components or processes to meet specified needs. PO4. Engineering Tools, Experimentation and Testing: Apply modern engineering tools and appropriate technique to conduct standard tests and measurements. PO5. Engineering practices for society, sustainability and environment: Apply appropriate technology in context of society, sustainability, environment and ethical practices. PO6. Project Management: Use engineering management principles individually, as a team member or a leader to manage projects and effectively communicate about well-defined engineering activities. PO7. Life-long learning: Ability to analyse individual needs and engage in updating in the context of tecnological changes (ix) Course Outcomes After completion of the course the students will be able to: CO-1: Suggest electrical/electronic component for given engineering application. CO-2: Test basic analogue circuits consist of OP-AMP. CO-3: Interpret the working of the digital circuits. CO-4: Use principles of electric and magnetic circuits in engineering applications. CO-5: Interpret the working of the A.C. circuits. CO-6: Operate transformers and electric motors for specific requirements safely. Expected Mapping with Programme Outcomes Course (1- Weak Correlation; 2- Medium correlation; 3- Strong Correlation) Outcomes PO-1 PO-2 PO-3 PO-4 PO-5 PO-6 PO-7 CO-1 3 2 2 3 1 1 1 CO-2 3 1 1 2 1 1 1 CO-3 3 1 1 - 1 1 1 CO-4 3 2 1 1 1 1 1 CO-5 3 2 1 2 1 1 1 CO-6 3 2 1 2 1 1 1 (xi) Abbreviations and Symbols List of Abbreviations Abbreviation Fullform Abbreviation Fullform Acm Common mode gain JFET Junction Field Effect transistor Ad Differential mode gain KCL Kirchhoff ’s Current Law AC Alternating Current KVL Kirchhoff ’s Voltage Law B Magnetic flux density LED Light Emitting Diode BJT Bipolar Junction Transistor LSB Least Significant Bit BW Band Width LV Low Voltage C Coulomb M Mutual Inductance CMOS Complementary Metal Oxide MOSFET Metal Oxide Field Effect Transistor Semiconductor CB Common Base MSB Most Significant Bit CC Common Collector OL Open loop CE Common Emitter OP-Amp Operational Amplifier CL Closed loop P Power CMRR Common Mode Rejection Ratio PIV Peak Inverse Voltage CO Course Outcome PO Program Outcome DC/ D.C./dc Direct Current PSRR Power Supply Rejection Ratio AC/ A.C./ac Alternating Current PVC Poly Vinyl Chloride emf electro motive force Q Quality factor FB Forward Biased R, L, C Resistor, Inductor, Capacitor FF FlipFlop RF DC or static resistance G Conductance RMS Root Mean Square Value Ge Germanium S, R Set, Reset H Magnetic field intensity Si Silicon HV High Voltage T Time period Hz Hertz t Time I Current TTL Transistor Transistor Logic i Instantaneous value of current UO Unit Outcome (xiii) IB Base current V Voltage IC Integrated Circuit VA Volt Ampere IC Collector current VAR Reactive Power IE Emitter current W Watt If Forward current Wb Weber IM Induction motor Y Admittance J Current density Z Impedance List of Symbols Symbol Description Symbol Description Ω SI unit of resistance, ohm αdc Current gain in CB configuration of a transistor µo Absolute permeability βdc Current gain in CE configuration of a transistor µr Relative permeability µ Permeability of a material Cf Feedback capacitor Α Temperature coefficient of resistance RC Reluctance of the magnetic core Θ Phase angle Rag Air gap reluctance Λ Flux linkage Rf Feedback resistor Ρ Specific resistance or resistivity fr Resonant frequency Σ Specific conductance or conductivity K Transformer turns ratio Φ Mutual flux Ø DC motor flux Ω Angular velocity (xiv) List of Figures Unit 1: Overview of Electronic Components and Signals Fig. 1.1: A basic circuit Fig. 1.2: Symbol of Resistors Fig. 1.3: Colour Coding of Resistors Fig. 1.4: Classification of Resistors Fig. 1.5: Parts of an inductor Fig. 1.6: Symbol of inductors Fig. 1.7: Symbol of a Capacitor Fig. 1.8: Series circuit Fig. 1.9: Parallel circuit Fig. 1.10: P N Junction Fig. 1.11: P N Junction Diode symbol Fig. 1.12: Diode-Forward bias Fig. 1.13: Diode-Reverse bias Fig. 1.14: Diode V–I characteristics Fig. 1.15: Structural diagram of NPN BJT Fig. 1.16: Schematic symbol of NPN and PNP BJT Fig. 1.17: FET Symbols Fig. 1.18: Depletion type MOSFET Fig. 1.19: Enhancement type MOSFET’s Fig. 1.20: CMOS device Fig. 1.21: Continuous time signal Fig. 1.22: Discrete time signal Fig. 1.23: Deterministic signal Fig. 1.24: Non-deterministic signal Fig. 1.25: Alternating Current signal Fig. 1.26: Direct Current signal Fig. 1.27: AC Voltage Sine waveform Fig. 1.28: Circuit representation of ideal voltage source Fig. 1.29: V-I characteristic of ideal voltage source Fig. 1.30: Circuit representation of ideal current source Fig. 1.31: V-I characteristic of ideal current source Fig. 1.32: Circuit representation of practical voltage source Fig. 1.33: V-I characteristics of practical voltage source Fig. 1.34: Circuit representation of current source Fig. 1.35: V-I characteristic of current source Fig. 1.36: Symbol of dependent voltage source Fig. 1.37: Symbol of dependent current source (xv) Unit 2: Overview of Analog Circuits Fig. 2.1: Symbol of Op Amp Fig. 2.2: Pin out diagram of IC μA 741 Fig. 2.3: Various IC packages of 741 Op Amp Fig. 2.4: Input bias currents IB1 and IB2 and offset voltage Vio Fig. 2.5: Ideal Op Amp Fig. 2.6: Op Amp closed loop configuration Fig. 2.7: Block diagram of Op Amp with feedback Fig. 2.8: Inverting Amplifier Fig. 2.9: Op Amp with negative feedback Fig. 2.10: Non-inverting Amplifier Fig. 2.11: Op Amp as an Adder circuit Fig. 2.12: Op Amp differentiator circuit Fig. 2.13: Ideal output waveforms using square and sine wave Fig. 2.14: Op Amp Integrator circuit Fig. 2.15: Ideal output waveforms using square and sine wave Unit 3: Overview of Digital Electronics Fig. 3.1: Logic signals Fig. 3.2: AND Gate Fig. 3.3: OR Gate Fig. 3.4: NOT Gate Fig. 3.5: NOR and NAND Gate Fig. 3.6: S-R latch using NAND gates Fig. 3.7: Clocked S-R Flip flop Fig. 3.8: D–Flip flop Fig. 3.9: J-K Flip flop Fig. 3.10: T-Flip flop Fig. 3.11: State Diagram Fig. 3.12: 2-bit UP Asynchronous counter Fig. 3.13: 2-bit DOWN Asynchronous counter Fig. 3.14: 4-bit Decade counter Fig. 3.15: Two input TTL logic NAND gate Unit 4: Electric and Magnetic Circuits Fig. 4.1: (a) Representation of voltage difference (b) Alternative representation of voltage Difference Fig. 4.2: (a) Passive sign convention of power dissipated (b) Passive sign convention of power generated Fig. 4.3: Node Fig. 4.4: Mesh Fig. 4.5: Illustration of KCL Fig. 4.6: Illustration of reference node Fig. 4.7: Flux lines produced by a single conductor Fig. 4.8: B-H curve of different types of magnetic material (xvi) Fig. 4.9: Flux Fig. 4.10: Ring of ferromagnetic material with exciting coil Fig. 4.11: Self Inductance Fig. 4.12: Mutual inductance Fig. 4.13: (a) Magnetic core with air gap (b) Electric circuit analogy of the magnetic circuit Fig. 4.14: (a) Magnetic structure with three limbs (b) Electrical analogy of the magnetic circuit Unit 5: AC Circuits Fig. 5.1: EMF generated in a Coil rotating in a magnetic field Fig. 5.2: Sinusoidal waveform Fig. 5.3: Alternating Voltage and Current Fig. 5.4: AC system and DC system Fig. 5.5: Three-Phase Sine Wave Fig. 5.6: Sine wave with phase angle Fig. 5.7: Phase of rotating coil Fig. 5.8: Phase Difference Fig. 5.9: Pure resistive current with AC source Fig. 5.10: Response of a pure Resistive circuit to AC voltage input Fig. 5.11: Phasor Diagram of resistive circuit Fig. 5.12: Pure Inductive circuit with AC input Fig. 5.13: Response of a pure Inductive circuit to AC voltage input Fig. 5.14: Phasor Diagram of a pure inductive circuit Fig. 5.15: Pure Capacitive Circuit with AC input Fig. 5.16: Response of a pure capacitive circuit to AC voltage input Fig. 5.17: Phasor Diagram a pure capacitive circuit Fig. 5.18: R-L Series circuit Fig. 5.19: Response of R-L series circuit to AC voltage input Fig. 5.20: R-C series circuit Fig. 5.21: Response of R-C series circuit to AC voltage input Fig. 5.22: R-L-C series circuit Fig. 5.23: Impedance Triangle Fig. 5.24: R-L-C parallel circuit Fig. 5.25: Phasor Diagram of parallel RLC Circuit Fig. 5.26: Star Connection Fig. 5.27: Delta Connection Fig. 5.28: Star connection with Voltage and Current Fig. 5.29: Delta connection with Voltage and Current Fig. 5.30: Power Triangle Unit 6: Transformer and Machines Fig. 6.1: Front View of a Transformer Fig. 6.2: Sectional view of a single phase core (xvii) Fig. 6.3: (a) Core type transformer (b) Shell type transformer Fig. 6.4: Elementary Transformer Fig. 6.5: Phasor diagram at No load Fig. 6.6: Autotransformer Fig. 6.7: Sectional view of a DC machine Fig. 6.8: DC Series Motor Fig. 6.9: DC Shunt Motor Fig. 6.10: Speed -Torque characteristics of a DC series motor Fig. 6.11: Speed-Torque characteristics of a DC shunt motor Fig. 6.12: 3- phase induction motor (a) Squirrel cage (b) Wound rotor Fig. 6.13: Torque in round rotor machine Fig. 6.14: Torque-Speed characteristics (a) 3-phase Induction motor (b) 3-phase Synchronous motor Fig. 6.15: 1-phase capacitor split phase motor (a) Connection diagram (b) Phasor diagram (xviii) List of Tables Unit 1: Overview of Electronic Components and Signals Table 1.1 : Formulae for parallel and series connection of elements Table 1.2 : Type of diodes Table 1.3 : Comparison of Transistor configuration Table 1.4 : Operating State and Junction Biasing Table 1.5 : Comparison between BJT and FET Table 1.6 : Comparison between passive and active components Unit 2: Overview of Analog Circuits Table 2.1 : Prefix Characters and Manufacturer Names for IC741 Table 2.2 : Pin Functions of IC 741 Table 2.3 : IC 741 Parameters Unit 3: Overview of Digital Electronics Table 3.1 : Boolean laws Table 3.2 : Comparison between Synchronous and Asynchronous sequential circuits Table 3.3 : Comparison of TTL subfamilies Table 3.4 : Popular Digital TTL IC’s Unit 4: Electric and Magnetic Circuits Table 4.1 : Analogy between electrical and magnetic circuits Unit 6: Transformer and Machines Table 6.1 : Rotor construction details of 3-phase AC Motor (xix) Guidelines for Teachers To implement Outcome Based Education (OBE) knowledge level and skill set of the students should be enhanced. Teachers should take a major responsibility for the proper implementation of OBE. Some of the responsibilities (not limited to) for the teachers in OBE system may be as follows: Within reasonable constraint, they should manipulate time to the best advantage of all students. They should assess the students only upon certain defined criterion without considering any other potential ineligibility to discriminate them. They should try to grow the learning abilities of the students to a certain level before they leave the institute. They should try to ensure that all the students are equipped with the quality knowledge as well as competence after they finish their education. They should always encourage the students to develop their ultimate performance capabilities. They should facilitate and encourage group work and team work to consolidate newer approach. They should follow Blooms taxonomy in every part of the assessment. Bloom’s Taxonomy Student should be Possible Mode of Assess- Level Teacher should Check able to ment Creating Students ability to create Design or Create Mini project Evaluating Students ability to Justify Argue or Defend Assignment Students ability to Differentiate or Analysing Project/Lab Methodology distinguish Distinguish Students ability to use Technical Presentation/ Applying Operate or Demonstrate information Demonstration Students ability to explain Understanding Explain or Classify Presentation/Seminar the ideas Students ability to recall (or Remembering Define or Recall Quiz remember) Guidelines for Students Students should take equal responsibility for implementing the OBE. Some of the responsibilities (not limited to) for the students in OBE system are as follows: Students should be well aware of each UO before the start of a unit in each and every course. Students should be well aware of each CO before the start of the course. Students should be well aware of each PO before the start of the programme. Students should think critically and reasonably with proper reflection and action. Learning of the students should be connected and integrated with practical and real life consequences. Students should be well aware of their competency at every level of OBE. (xxi) Contents Forward....................................................................................................................................................................................................... iii Acknowledgment v Preface vii Outcome based Education........................................................................................................................................................................ ix Course Outcomes....................................................................................................................................................................................... xi Abbreviations and Symbols.................................................................................................................................................................... xiii List of Figures............................................................................................................................................................................................ xv List of Tables............................................................................................................................................................................................. xix Guidelines for Teachers........................................................................................................................................................................... xxi Guidelines for Students........................................................................................................................................................................... xxi Unit 1: Overview of Electronic Components and Signals................................................................................................1-64 Unit Specifics................................................................................................................................................................................... 1 Rationale.......................................................................................................................................................................................... 1 Pre-requisites.................................................................................................................................................................................. 1 Unit Outcomes................................................................................................................................................................................ 2 1.1 Passive Components...................................................................................................................................................................... 2 1.1.1 Introduction........................................................................................................................................................................ 2 1.1.2 Types of Circuit Elements................................................................................................................................................. 2 1.1.3 Resistance............................................................................................................................................................................ 3 1.1.4 Inductors............................................................................................................................................................................. 5 1.1.5 Capacitors........................................................................................................................................................................... 6 1.1.6 Series and Parallel Circuits............................................................................................................................................... 7 Solved Problems............................................................................................................................................................................. 8 1.2 Active Components........................................................................................................................................................................ 9 1.2.1 Introduction........................................................................................................................................................................ 9 1.2.2 P N Junction Diode............................................................................................................................................................ 9 1.2.3 Transistors........................................................................................................................................................................ 12 1.2.4 FET..................................................................................................................................................................................... 15 1.2.5 MOS Devices.................................................................................................................................................................... 16 1.2.6 CMOS................................................................................................................................................................................ 17 1.2.7 Comparison between Passive and Active Components............................................................................................. 18 Activities........................................................................................................................................................................................ 18 Solved Problems.......................................................................................................................................................................... 18 1.3 Signals and Active Sources.......................................................................................................................................................... 19 1.3.1 Introduction...................................................................................................................................................................... 19 1.3.2 Classification of Signals................................................................................................................................................... 19 1.3.3 Deterministic and Non-Deterministic Signals............................................................................................................ 19 (xxiii) 1.3.4 Periodic and Non-periodic Signals................................................................................................................................ 20 1.3.5 Electrical Signals............................................................................................................................................................... 20 1.3.6 Voltage and Current Sources......................................................................................................................................... 22 1.3.7 Ideal/Non-Ideal Sources................................................................................................................................................. 22 1.3.8 Dependent Voltage and Current Source...................................................................................................................... 24 Applications................................................................................................................................................................................. 24 Activities........................................................................................................................................................................................ 24 Solved Problems........................................................................................................................................................................... 25 Unit Summary............................................................................................................................................................................... 26 Exercises......................................................................................................................................................................................... 26 Practicals....................................................................................................................................................................................... 28 Know More.................................................................................................................................................................................... 63 References and Suggested Readings........................................................................................................................................... 64 Unit 2: Overview of Analog Circuits............................................................................................................................... 65-86 Unit Specifies................................................................................................................................................................................. 65 Rationale........................................................................................................................................................................................ 65 Pre-requisites................................................................................................................................................................................ 65 Unit Outcomes.............................................................................................................................................................................. 65 2.1 Fundamentals of Operational Amplifiers................................................................................................................................. 66 2.1.1 Introduction...................................................................................................................................................................... 66 2.1.2 Basics of Op Amp............................................................................................................................................................. 66 2.1.3 Ideal Op Amp................................................................................................................................................................... 70 2.1.4 Op Amp Configurations................................................................................................................................................. 71 2.1.5 Op Amp Operating Modes............................................................................................................................................. 72 Solved Problems........................................................................................................................................................................... 75 2.2 Applications of Operational Amplifiers................................................................................................................................... 76 2.2.1 Op Amp as an Adder....................................................................................................................................................... 76 2.2.2 Op Amp as a Differentiator............................................................................................................................................ 77 2.2.3 Op Amp as an Integrator................................................................................................................................................ 78 Applications.................................................................................................................................................................................. 80 Activity for Inquisitiveness and Curiosity................................................................................................................................ 80 Solved Problems.......................................................................................................................................................................... 80 Unit Summary............................................................................................................................................................................... 81 Exercises......................................................................................................................................................................................... 81 Practical.......................................................................................................................................................................................... 82 Know More.................................................................................................................................................................................... 85 References and Suggested Readings........................................................................................................................................... 86 (xxiv) Unit 3: Overview of Digital Electronics....................................................................................................................... 87-104 Unit Specifies................................................................................................................................................................................. 87 Rationale........................................................................................................................................................................................ 87 Pre-requisites................................................................................................................................................................................ 87 Unit Outcomes.............................................................................................................................................................................. 87 3.1 Boolean Operation and Boolean Algebra.................................................................................................................................. 88 3.1.1 Introduction...................................................................................................................................................................... 88 3.1.2 Number System................................................................................................................................................................ 88 3.1.3 Number Conversion........................................................................................................................................................ 89 3.1.4 Binary Arithmetic............................................................................................................................................................ 90 3.1.5 Boolean Laws and Theorems.......................................................................................................................................... 90 Activity........................................................................................................................................................................................... 91 Solved Problems.......................................................................................................................................................................... 91 3.2 Logic Gates.................................................................................................................................................................................... 92 3.2.1 Positive and Negative Logic............................................................................................................................................ 92 3.2.2 Types of Logic Gates........................................................................................................................................................ 92 Activity........................................................................................................................................................................................... 94 Solved Problems........................................................................................................................................................................... 94 3.3 Flip Flops and Counters.............................................................................................................................................................. 95 3.3.1 Types of Flip-Flops.......................................................................................................................................................... 95 3.3.2 Counters........................................................................................................................................................................... 97 Activities........................................................................................................................................................................................ 98 Solved Problems.......................................................................................................................................................................... 98 3.4 Digital Integrated Circuits........................................................................................................................................................... 99 3.4.1 Introduction to Integrated Circuits............................................................................................................................... 99 3.4.2 Digital IC Specification Terminology........................................................................................................................... 99 3.4.3 Transistor Transistor Logic (TTL)................................................................................................................................ 99 3.4.4 TTL Sub families............................................................................................................................................................ 100 3.4.5 Digital IC’s applications................................................................................................................................................ 101 Activities...................................................................................................................................................................................... 101 Solved Problem........................................................................................................................................................................... 101 Unit Summary............................................................................................................................................................................. 101 Exercises....................................................................................................................................................................................... 102 Know More.................................................................................................................................................................................. 103 References and Suggested Readings......................................................................................................................................... 104 Unit 4: Electric and Magnetic Circuits....................................................................................................................... 105-122 Unit Specifies............................................................................................................................................................................... 105 Rationale...................................................................................................................................................................................... 105 (xxv) Pre-requisites.............................................................................................................................................................................. 105 Unit Outcomes............................................................................................................................................................................ 105 4.1 Parameters of an Electric Circuit............................................................................................................................................. 106 4.1.1 Introduction.................................................................................................................................................................... 106 4.1.2 Current /Voltage and Power/Energy.......................................................................................................................... 106 4.1.3 Electric Circuit Terminology........................................................................................................................................ 107 4.1.4 Circuit Analysis............................................................................................................................................................. 108 Activity......................................................................................................................................................................................... 110 Solved Problem........................................................................................................................................................................... 110 4.2 Parameters of a Magnetic Circuit............................................................................................................................................. 110 4.2.1 Magnetic Effect of Electric Current............................................................................................................................. 110 4.2.2 Magnetic Circuits........................................................................................................................................................... 112 Activity......................................................................................................................................................................................... 113 Solved Problems........................................................................................................................................................................ 113 4.3 Electromagnetic Induction........................................................................................................................................................ 113 4.3.1 Faradays law.................................................................................................................................................................... 113 4.3.2 Self and Mutual Inductance.......................................................................................................................................... 114 Activity......................................................................................................................................................................................... 115 Solved Problem........................................................................................................................................................................... 115 4.4 Analogy between Electrical and Magnetic Circuits............................................................................................................... 116 Activities...................................................................................................................................................................................... 117 Solved Problem.......................................................................................................................................................................... 117 Exercises....................................................................................................................................................................................... 118 Practical........................................................................................................................................................................................ 120 Know More.................................................................................................................................................................................. 122 References and Suggested Readings......................................................................................................................................... 122 Unit 5: AC Circuits..................................................................................................................................................... 123-148 Unit Specifies............................................................................................................................................................................... 123 Rationale...................................................................................................................................................................................... 123 Pre-requisites.............................................................................................................................................................................. 123 Unit Outcomes............................................................................................................................................................................ 123 5.1 Alternating Current Fundamentals......................................................................................................................................... 124 5.1.1 Introduction.................................................................................................................................................................... 124 5.1.2 Alternating Quantity.................................................................................................................................................... 124 5.1.3 Important terms related with an Alternating Quantity........................................................................................... 125 5.1.4 Phase, Phase Difference and Power Factor............................................................................................................... 128 5.1.5 Phasor.............................................................................................................................................................................. 129 5.1.6 AC in Pure Resistors, Inductors and Capacitors....................................................................................................... 129 Applications............................................................................................................................................................................... 131 (xxvi) Solved Problem........................................................................................................................................................................... 131 5.2 AC Series and Parallel Circuits................................................................................................................................................. 132 5.2.1 Introduction.................................................................................................................................................................... 132 5.2.2 Resistance - Inductance (R-L) Circuit......................................................................................................................... 132 5.2.3 Resistance - Capacitance (R-C) Circuit...................................................................................................................... 133 5.2.4 Resistance, Inductance and Capacitance Circuit (R.L.C.) Circuit.......................................................................... 134 Solved Problems......................................................................................................................................................................... 136 5.3 AC Power and Three Phase Circuit........................................................................................................................................ 137 5.3.1 Introduction................................................................................................................................................................... 137 5.3.2 Advantages of Three Phase System.............................................................................................................................. 137 5.3.3 Star and Delta Connection........................................................................................................................................... 138 5.3.4 Relationship between Line and Phase Values of Voltages and Currents............................................................... 138 5.3.5 Electric Power................................................................................................................................................................. 139 5.3.6 Power Triangle............................................................................................................................................................... 139 5.3.7 Power in Three Phase Connection.............................................................................................................................. 140 Activity......................................................................................................................................................................................... 140 Solved Problems........................................................................................................................................................................ 140 Unit Summary............................................................................................................................................................................. 141 Exercises....................................................................................................................................................................................... 141 Practicals...................................................................................................................................................................................... 143 Know More................................................................................................................................................................................ 148 References and Suggested Readings......................................................................................................................................... 148 Unit 6: Transformer and Machines........................................................................................................................... 149-174 Unit Specifies............................................................................................................................................................................... 149 Rationale...................................................................................................................................................................................... 149 Pre-requisites.............................................................................................................................................................................. 149 Unit Outcomes............................................................................................................................................................................ 149 6.1 Transformer................................................................................................................................................................................ 150 6.1.1 Introduction.................................................................................................................................................................... 150 6.1.2 Parts of a Transformer.................................................................................................................................................. 150 6.1.3 Types of Transformers.................................................................................................................................................. 152 6.1.4 Autotransformer............................................................................................................................................................ 155 Activities...................................................................................................................................................................................... 156 Solved Problems......................................................................................................................................................................... 156 6.2 Electric Motors............................................................................................................................................................................ 157 6.2.1 Introduction.................................................................................................................................................................... 157 6.2.2 DC Motor........................................................................................................................................................................ 157 6.2.3 AC Motors...................................................................................................................................................................... 161 6.2.4 Single phase AC Motor................................................................................................................................................. 163 (xxvii) Activities...................................................................................................................................................................................... 164 Solved Problems......................................................................................................................................................................... 164 Unit Summary............................................................................................................................................................................. 165 Exercises....................................................................................................................................................................................... 165 Practical........................................................................................................................................................................................ 166 Know More: Micro-project(s), Activities, Video Resources................................................................................................ 174 References and Suggested Readings......................................................................................................................................... 174 Appendices......................................................................................................................................................................... 175 Appendix - A: Lab Assessment Record................................................................................................................................... 175 Appendix - B: Instructions when working in the Laboratory............................................................................................. 176 Appendix - C: Indicative Evaluation Guidelines for Practicals.......................................................................................... 177 Answers to Objective Questions....................................................................................................................................... 178 References for Further Learning........................................................................................................................................ 179 CO and PO Attainment Table........................................................................................................................................... 180 Index............................................................................................................................................................................ 181-183 (xxviii) Overview of 1 Electronic Components and Signals UNIT SPECIFICS This unit discusses the following topics: Passive and active components Resistors, capacitors and inductors Diodes and their applications Bipolar Junction Transistors and their applications Field Effect Transistors, MOS and CMOS and their applications Signals: DC/AC, voltage/current, periodic/non-periodic signals Average, rms, peak values of signals Different types of signal waveforms Voltage and current sources The practical applications of the topics are discussed for generating further curiosity as well as improving problem solving capacity. Besides giving a number of multiple choice questions as well as questions of short and long answer types belonging to different categories following lower and higher order of Bloom’s taxonomy, number of numerical problems are provided for practice. The related practicals are provided based on the content of Unit 1, followed up by a “Know More” section. This section mainly contains “micro project and activities” that highlights the practical activity, examples of some interesting applications focusing on self-learning, creativity and developing outcomes in all the domains of learning. This has been incorporated so that the supplementary information provided through this part, becomes beneficial for the users of the book. It is important to note that for getting more information on various topics of interest, QR code of videos and websites have been provided that can be scanned and viewed for relevant supportive knowledge in between as well as in the “Know More” section. In the end, list of references and suggested readings are given in the unit so that one can go through them for further reading and practice. RATIONALE The wired world and human beings are dependent on electricity to perform many activities. Number of applications are controlled by electrical and electronic circuits, from miniature ones in integrated circuits in mobile phones and music players, to the computers and TV sets, to massive ones that carry power to the homes. This unit is a basic theme in the study of fundamentals of electrical and electronics engineering. In this unit, working of components like resistors, capacitors, inductors, diodes, BJT, FET that are basic constituents of any circuit are described. Signals that aids in analyzing, processing and validating the circuits and an overview of active sources which can deliver or absorb energy continuously are also explained in this unit. PRE-REQUISITE 1. Science: Effects of Current , Chemical Substances-Nature and Behaviour (Class X) 2. Applied Chemistry: Atomic Structure, Engineering Materials (Semester I) 3. Applied Physics-I: Physical world, Units and Measurements (Semester I) 4. Mathematics-1: Trigonometry, Algebra (Semester I) 2 Fundamentals of Electrical and Electronics Engineering UNIT OUTCOMES Upon completion of this unit, the student will be able to: U1-O1: Classify electronic and electrical components. U1-O2: Suggest suitable discrete components for a given application. U1-O3: Describe the construction and working principle of a given semiconductor devices. U1-O4: Interpret parameters of continuous electrical signals. U1-O5: Compare ideal and practical active sources. Unit-1 EXPECTED MAPPING WITH COURSE OUTCOMES Outcomes (1- Weak Correlation; 2- Medium correlation; 3- Strong Correlation) CO-1 CO-2 CO-3 CO-4 CO-5 CO-6 U1-O1 3 - - - - - U1-O2 3 - - - - - U1-O3 3 - - - - - U1-O4 - - - - - - U1-O5 - - - - - - Georg Simon Ohm (1789-1854) began his research with the electrochemical cell, invented by Italian scientist Alessandro Volta. His practical experiments showed the mathematical links and he found that there is a direct proportionality between the potential differences (voltage) applied across a conductor and the resultant electric current, provided the temperature does not change. This relationship is known as Ohm’s law and is now a cornerstone of electrical circuit design. 1.1 PASSIVE COMPONENTS 1.1.1 Introduction Teenagers as well as children love to play jig saw puzzles. Number of discrete parts have to be properly placed together in the puzzle to develop a complete picture. Each part has a specific role in the developed picture. Similarly, for any electrical or electronics application, circuits or systems are developed in which each component has a specific meaningful role for the application to become operational. In fact, it is possible to assemble a circuit without really understanding the different parts involved. One can just connect components together like jigsaw puzzle to match an electronic schematic. That said, in order to debug an existing circuit or design one, it is important to actually understand how the individual electrical components work and how to use them together. In this topic working of components like resistors, capacitors, and inductors that are basic constituents of any circuit will be described. Passive 1.1.2 Types of Circuit Elements component Electronic elements also known as components that make up a circuit are connected together by conductors to form a complete Active component circuit. They can be classified into two main categories depending on whether they deliver or absorb energy from the circuit: a. Passive components b. Active components A passive component can only receive energy, which it can either dissipate or absorb. An active component supplies energy to an Fig. 1.1: A basic circuit Overview of Electronic Components and Signals 3 electric circuit, and hence has the ability to electrically control the flow of charge. An example of a basic circuit made up of two electronic elements, a cell and a bulb has been illustrated in Fig.1.1. Discrete components The components, which are discrete in nature i.e. with just one circuit element, are called discrete components. These components may be active or passive in nature. They are widely used in electrical and electronic circuits. Some of the discrete components are Resistors, Capacitors, Inductors, Semiconductor diodes, Transistors. The term discrete component should be understood as it is used to differentiate discrete components from integrated circuits (ICs) which contain Resistor multiple different circuit elements. Definition of a passive component A passive component is an electronic component when connected in a circuit can only receive energy, which it can either dissipate, absorb or store it in an electric field or a magnetic field. Passive elements do not need any form of electrical power to operate. As the name ‘passive’ suggests – passive devices do not provide gain or amplification. Common examples of passive components include Resistors, Inductors, Capacitors. 1.1.3 Resistance Resistance is the opposition to current flow in an electrical circuit. It is described as the property of a substance due to which it opposes the flow of current through it. Resistance is not same for all materials. Conductors like copper, aluminum etc. offer small resistances whereas insulating materials like Bakelite, glass, rubber, mica, dry wood, p.v.c. (polyvinyl chloride), etc. offer high resistance. The higher the resistance provided by a material, the lower the flow of electrons or current through the material. The property of resistance is used in a wide variety of applications and appliances such as computer mother board, televisions and incandescent lamps. The SI unit for resistance is the ohm, symbolized by the Greek letter Ω (omega) and also represented by letter R. Resistance of a material is one ohm when a current of one ampere passes through a material with a voltage of one volt. The current is proportional to the voltage across the terminal ends. This ratio is represented by Ohms law: V...(1.1) R= I The resistance R offered by a conductor depends on the following four factors: a. It varies directly as its length, ‘l’. b. It varies inversely as the cross-section area ‘A’ of the conductor. c. It is dependent upon the nature of the material. d. It also depends on the temperature of the conductor. Neglecting the last factor for the present, ρl R α l or R =...(1.2) A A Where ρ is a constant depending on the nature of the material and is known as its specific resistance or resistivity. The unit of specific resistance is ohm-meter. Resistors The resistor is an electrical component with two terminals. It is one of the most important components in a circuit as it allows the user to precisely control the amount of current and voltage in the circuit. Resistors can be divided in terms of construction type as well as resistance material. A resistor though very small, is often made up of copper wires coiled around a ceramic rod and an outer coating of insulating paint. This is called a wire-wound resistor, and the number of turns and the size of the wire determine the precise amount of resistance. Smaller resistors, those that are designed and used for low-power circuits, are often made out of carbon film, which replaces the wound of copper wire that can be bulky. Fig. 1.3 shows Colour Coding of carbon film resistors, which is described in 4 Fundamentals of Electrical and Electronics Engineering Fixed Value Fixed Value Variable Re- Fixed Value Resistor Resistor sistor Resistor (ICE Symbol) (IEEE Symbol) (IEC Symbol) (IEC Symbol) Fig. 1.2: Symbol of Resistors Fig. 1.3: Colour Coding of Resistors Fig. 1.4: Classification of Resistors Power rating or wattage The maximum amount of heat dissipated by a resistor at maximum specified temperature without damage to resistor is called power rating of a resistor. It is expressed in watt (W) at specified temperature. When resistor is used at higher temperature, power rating will be decreased. The normal available resistors have power ratings of 1/8 W, 1/4 W, 1/2 W, 1 W, 2 W. The size of a resistor depends on its power handling capacity. Small resistors are designed to handle low powers,as size of resistor increases power handling capacity also increases. Conductance and conductivity The reciprocal of resistance is called as Conductance, represented by letter ‘G’. Whereas resistance of a conductor measures the opposition which it offers to the flow of current, the conductance measures the inducement which it offers to its flow. From Eq. 1.2 l G=1 l R= ρ ρ A A G=σ A...(1.3) l where σ is called the conductivity or specific conductance of a conductor. The unit of conductance is Siemens (S). The unit of conductivity is Siemens/metre (S/m). Overview of Electronic Components and Signals 5 Effect of temperature on resistance One of the factors that effects resistance of any material is temperature.The effect of rise in temperature is: a. to increase the resistance of pure metals. b. to decrease the resistance of carbon, electrolytes, and insulators. c. to increase the resistance of alloys, though in their case, the increase is relatively small. Temperature coefficient of resistance Let a metallic conductor having a resistance of R₀ at 0°C be heated of t°C and let its resistance at this temperature be Rt. Then, considering normal ranges of temperature, it is found that the increase in resistance, Rt−R₀ depends a. directly on its initial resistance b. directly on the rise in temperature c. on the nature of the material of the conductor. or Rt− R₀ α R₀ × t or Rt − R₀ = αR₀t...(1.4) where α (alpha) is a constant and is known as the temperature coefficient of resistance of the conductor. Rearranging Eq. (1.4) results in Rt = R₀ + α R₀t = R₀ (1+ αt)...(1.5) 1.1.4 Inductors Inductor is a two-terminal component that temporarily stores energy in the form of a magnetic field. It is usually called as a coil. The main property of an inductor is that it opposes any change in current. An inductor is also considered as passive element of circuit, because it can store energy in it as a magnetic field, and can deliver that energy to the circuit, but not in continuous basis. The energy absorbing and delivering capacity of an inductor is limited.. According to the Faraday’s law of Electromagnetic induction, when the current flowing through an inductor changes, the time-varying magnetic field induces a voltage in the conductor. According to Len's law, the direction of induced EMF opposes the change in current that created it. Hence, induced EMF is opposite to the voltage applied across the coil. This is the property of an inductor. An inductor blocks any AC component present in a DC signal. The inductor is sometimes wrapped upon a core, for example a ferrite core. Fig.1.5 shows an inductor with various parts labelled. Fig.1.5: Parts of an inductor Fig.1.6: Symbol of inductors Symbol and units The symbols of various types of inductors are as given in Fig.1.6. The unit of inductance is Henry i.e. H. In actual practice, Henry is an extremely large unit. Therefore, much smaller units are used like millihenry (mH) or microhenry (μH). 1 mH = 1 × 10–3 H and 1μH = 1 × 10-⁶ H. Factors affecting inductance The inductance of a coil depends upon the following parameters: 1. Number of turns, N 2. Core material 6 Fundamentals of Electrical and Electronics Engineering 3. Length of winding 4. Dimension of coil former Storage of energy in inductor One of the basic properties of electromagnetism is that the current when flows through an inductor, a magnetic field gets created perpendicular to the current flow. This keeps on building up. It gets stabilized at some point, which means that the inductance won’t build up after that. When the current stops flowing, Coil the magnetic field gets decreased. This magnetic energy gets turned into electrical energy. Hence energy gets Tutorial stored in this temporarily in the form of magnetic field. Q Factor of an inductor The ability of an inductor to store energy as compared to the dissipation of energy within the inductor is called Quality (or Q) factor. It is also known as figure of merit. The Q factor is given by, Energy Stored Q=...(1.6) Energy Dissipated A high Q factor means little energy dissipation with respect to energy storage, while a low Q factor means energy dissipation as large as energy storage. The value of Q factor for coils may range between 5 to 100. It may be noted that smaller the value of DC resistance of a coil, higher is the value of Q factor. The high Q coils are preferred in tuning circuits, because it makes the circuit more selective and sensitive 1.1.5 Capacitors A capacitor is a passive component that has the ability to store the energy in the form of potential difference between its plates. It resists a sudden change in voltage. The charge is stored in the form of potential difference between two plates, which form to be positive and negative depending upon the direction of charge storage. A non-conducting region is present between these two plates which is called as dielectric. This dielectric can be vacuum, air, mica, paper, ceramic, aluminium etc. The name of the capacitor is given as per the dielectric used. Symbol and units The standard units for capacitance is Farads. Generally, the values of capacitors available will be in the order of micro-farads, pico-farads and nano-farads. The symbol of a capacitor is as shown in Fig.1.7. The capacitance of a capacitor is proportional to the distance between the plates and is inversely proportional to the area of the plates. Also, the higher the permittivity of a material, the higher will be the capacitance. The permittivity of a medium describes how much electric flux is being generated per unit charge in that medium. Dielectric materials used in a capacitor Fig.1.7: Symbol of a Capacitor The dielectric materials used in manufacturing of capacitor are as under: 1. Air 2. Mica 3. Glass 4. Ceramic 5. Porcelain 6. Polystyrene 7. Fibre 8. Bakelite 9. Waxed paper 10. Electrolyte Overview of Electronic Components and Signals 7 Functions of a capacitor The important functions of a capacitor in the electric circuit are as given below : 1. It opposes the flow of direct current (D.C.) through it. 2. It bypasses the alternating current (A.C.) through it very easily. 3. It stores the electric energy in it. Capacitor 4. It removes the ripple from D.C. power supply. Types 5. It opposes any change of voltage in the circuit. 1.1.6 Series and Parallel Circuits Resistors connected in such a way that current from one flow only into another are said to be connected in series. The series combination of two resistors as shown in Fig.1.1.8 acts, as far as the voltage source is concerned, as a single resistor having a value equal to the sum of the two resistances. Fig. 1.8: Series circuit Fig. 1.9: Parallel circuit For circuits having resistances connected in parallel as shown in Fig. 1.9 Similar to resistance, when capacitance and inductances are connected in series and parallel in circuits, Table 1.1 shows the formula for equivalent value. Table 1.1: Formulas for Parallel and Series connection of elements Type of Connection Resistor Inductor Capacitor 1 1+1 Series R = R1 + R2 L = L1 +L2 = C C1 C2 1 =1+1 1= 1 + 1 Parallel R R1 R2 C = C1 +C2 L L1 L2 Applications of passive components in Real life Passive components are used in number of devices. Some of the uses will be explained in later units. Resistors Following are the applications of resistors: 1. Potential dividers 2. Current control 3. D.C. power supplies 4. Filter circuit networks 5. Amplifier circuits 6. Heating element 8 Fundamentals of Electrical and Electronics Engineering Some other applications include For protection purposes, e.g. fusible resistors. Wire wound resistors find application where balanced current control, high sensitivity, and accurate measurement are required like in shunt with ampere meter. Photo resistors find application in flame detectors, burglar alarm, in photographic devices, etc. Capacitors The important applications of capacitor in electronic circuits are as given below : 1. It is used for the storage of energy. 2. It is used in the filter circuits to minimize the ripple voltage. 3. It is used in the tuning circuits for selection of frequency. 5. It is used for starting the motor, for running the motor 6. It is used for equipment like SMPS, Modem. Inductors The important applications of inductors are as given below: 1. It is used to minimize the ripples alternating current in a circuit. 2. It is used for allowing the flow of direct current. 3. It is used in filter circuits to minimize the ripple voltage or ripple factor. 4. It is used in tuning circuits of radio transmitters and receivers to select the frequency. 5. It is used in devices like Relays, Electric Motors, Transformers, Sensors Solved Problems Example 1.1.1: Five resistors with resistances of 2.2 Meg ohms, 470 KΩ, 220 KΩ, 55 KΩ, and 1.6 Mega ohms are connected in series. Calculate the total or equivalent resistance of this series combination? Solution: For series combination of resistances, the equation is Req = R1 + R2 + R3 + R4 + R5 However, there is a note of caution that all the resistances must be expressed in terms of the same unit. In terms of kilo ohms we have Req = 2200 + 470 + 220 + 55 + 1600 Req = 4545 kΩ Req = 4.545 Mega ohms Example 1.1.2: Four resistors with resistances of 1 kΩ, 2 kΩ, 4 kΩ, and 8 kΩ are connected in parallel. Calculate the equivalent resistance of this combination? Solution: For parallel combination of resistances, the equation is 1 = 1 + 1 + 1 + 1 Req R1 R 2 R 3 R 4 1 =1 +1 +1 +1 Req 1 2 4 8 = 0.125 + 0.250 + 0.500 + 1.000 = 1.875 Then 1 Req = _____ = 0.53kΩ 1.875 Overview of Electronic Components and Signals 9 1.2 ACTIVE COMPONENTS 1.2.1 Introduction Automation, Digitization and Smart system requires use of active components. Active components play a vital role in all engineering disciplines and engineering application ranging from domestic to industrial, space, defense, agriculture, medical, transportation, education and entertainment. All electronic products are based on functioning of active components. The components which operation changes as per external energy are termed as active components. Active components performance relies on external energy. Active components are suitable for rectifying, amplifying and switching applications. Two main types of active components are: 1) Tube devices 2) Semiconductor devices. Now a days tube devices are not commonly used as they exhibits many drawbacks such as low speed of operation, larger size, difficult for mounting and expensive than semiconductor components. Semiconductor active components are also called as solid state components. These are made up of semiconductor materials. Active semiconductor components have many advantages such as: high speed of operation ,compactness, easy for mounting and cheaper than tube devices. Commonly used active components are diode, BJTs (Bipolar Junction Transistors) , FET (Field Effect Transistor), MOSFET (Metal Oxide Semiconductor FET), SCR (Silicon controlled Rectifier), DIAC, UJT (Uni Junction Transistor), TRIAC , IGBT, PUT and Integrated circuits. Semiconductor material has electrical conductivity less than conductor and more than insulator. Its conductivity changes as per application of external energy. Pure semiconductor materials are called as intrinsic semiconductor. Commonly used pure semiconductor materials are Silicon (Si) and Germanium (Ge). To improve conductivity i.e. free charge carriers, impurity is added to intrinsic semiconductor. The process of addition of impurity to intrinsic semiconductor is called as doping. Due to doping process intrinsic semiconductor is converted into impure semiconductor. This impure semiconductor material is called as extrinsic semiconductor. Depend on type of impurity material added to intrinsic semiconductor, two types of extrinsic semiconductor are obtained such as P type and N type material. By using these two extrinsic semiconductor active components are constructed. To obtain P type extrinsic semiconductor trivalent material and to obtain N type extrinsic semiconductor pentavalent impurity material is added. In P type material positive charge carrier Holes are majority charge carrier while in N type. 1.2.2 P N Junction Diode A P-N junction diode is formed by connecting P and N type semiconductors. As soon as the P-N junction is formed, it results in the following processes: 1. Holes from P region near the junction diffuse into N region and combine with free electrons. Similarly, free electrons from N region and near the junction enter P region to recombine with holes. 2. These re-combinations near the junction do not continue for a long because electrons trying to diffuse into P region are now repelled by the negative immobile ions and the holes from P region are repelled by positive immobile ions in the N region. So total recombination of holes and electrons cannot occur. 3. Due to few re-combinations near the junction, a region is formed on both sides with no charge carriers. It contains only negative and positive immobile ions. This region is called depletion region or space-charge region Fig.1.10 shows P N junction with depletion region. P N Depletion region Fig. 1.10: P N Junction 10 Fundamentals of Electrical and Electronics Engineering The electric field between the acceptor and donor ions is called barrier. The potential difference between the two sides of barrier, i.e., barrier potential is about 0.7 V for Si and 0.3 V for Ge P-N junction. P-N junction diode is a two terminal device. The terminal connected to the P region is called anode. The terminal connected to N region is called cathode. There are two electrodes, hence the name diode (DI + electrode).The symbol of a P-N junction diode is as shown in Fig. 1.11. A K Fig. 1.11: P N junction Diode symbol 1.2.2.1 Operation of P-N junction diode The P N junction diode can be operated in two states or conditions namely forward bias state and reverse bias state. When anode is at higher potential with respect to cathode, the diode is said to be in forward bias, i.e., connecting positive terminal of the external battery to anode and negative terminal to the cathode. Fig. 1.12 shows diode forward bias connection. Holes from the P region are repelled by the positive terminal of the battery and move towards the junction. Similarly electrons from N region move towards the junction. So the width of depletion region decreases. Holes Electrons P N A K + – V Fig. 1.12: Diode-Forward bias The direction of conventional current is the direction of movement of holes, i.e., from anode to cathode. If the battery voltage is increased, the current also increases. Very little current flows due to minority carriers in opposite direction. When the anode is at lower potential with respect to cathode (negative w.r.t. cathode), the P-N junction is said to be reverse biased, i.e. negative terminal of the external battery is connected to the anode and positive terminal to the cathode. Holes from P region are attracted towards the negative terminal of the battery and the electrons from N region move towards the positive terminal of the battery. Since the carriers move away from the junction, the width of depletion region increases. Thus there is no current due to majority carriers. But there is very small current from cathode to anode due to minority carriers. These are very less in number so the current is also very small. Holes Electrons P N A K + – VR Fig. 1.13: Diode-Reverse bias Overview of Electronic Components and Signals 11 1.2.2.2 Characteristics of a diode V I Characteristics of a device shows device operation for various applied input voltages. The forward and reverse characteristics of diode is as shown in Fig. 1.14. Fig. 1.14: Diode V–I characteristics The diode connected in a DC circuit offers a definite resistance which is called DC resistance or static resistance. It is the ratio of DC voltage across the diode to the DC current through the diode (Eq. 1.10). V RF =...(1.7) I As seen from the forward characteristics nature, the static resistance is small in few ohms i

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