ELECTRIC CIRCUITS & ELECTRONICS for Universities (Textbook)

Electric Current If dq coulombs of charge flow across any cross-section of a conductor in time dt, then the magnitude of the current I flowing through it is given by : dq I dt  Thus an electric current may be defined as the rate of flow of electric charges across any cross-section of a conductor. The S.I. unit of current is ampere and is denoted as A. One ampere current is said to flow through a conductor when a charge of 1 coulomb passes through any crossection in 1 second. 1 A = 1 C/ 1 s 1 mA = 10-3 A, 1 µA = 10-6 A  In metals, the carriers of electric current are negatively charged electrons.  As a matter of convention, the direction of electric current is taken as the direction of flow of positive charges.  In electrolytes, the carriers of electric current are ions.  The amount of charge flowing through a crossection of a conductor from t = t i to t = t f is given by : f i t t q I dt   Specific Resistance or Resistivity :

Electric circuit theory and electromagnetic theory are the two fundamental theories upon which all branches of electrical engineering are built. Many branches of Electrical Engineering, such as power, electric machines, control, electronics, communications, and instrumentation, are based on electric circuit theory. Therefore, the basic electric circuit theory course is the most important course for an Electrical Engineering student, and always an excellent starting point for a beginning student in Electrical Engineering education.

2023

Ohm's Law has long been a cornerstone of electrical engineering, providing a linear relationship between voltage, current, and resistance that has underpinned modern circuit analysis. However, as technology advances and philosophical inquiries deepen, the limitations of this venerable law have become evident, particularly in scenarios involving near-zero resistance. This paper introduces a novel formulation-the modified Ohm's Law; that not only rectifies the pitfalls of the conventional law but also harmonizes physics with philosophical principles. Motivated by the perplexing issue of predicting infinite current at zero resistance and the philosophical implications of deriving infinity from the finite, the modified equation serves as a bridge between empirical insights and logical coherence. Through rigorous mathematical derivation, comprehensive theoretical examination, and scrupulous computational analysis, the accuracy and applicability of the modified Ohm's Law are not only demonstrated but also its suitability across a wide range of scenarios is revealed. These scenarios include semiconductor devices, high-current applications, and complex systems where the standard Ohm's Law falls short, offering a transformative perspective on the analysis of electrical circuitry. In reconciling scientific rigor with philosophical consistency, this paper advances our understanding of electrical circuitry and beckons a new era of precision in analysis. Further, the modified Ohm's Law paves the way for deeper explorations that resonate through the domains of physics and philosophy, reshaping the landscape of our understanding.

'Electrical Circuit Theory and Technology, Revised second Edition' provides coverage for a wide range of courses that contain electrical principles, circuit theory and technology in their syllabuses, from introductory to degree level. The chapter 'Transients and Laplace transforms', which had been removed from the second edition due to page restraints, has been included in this edition in response to popular demand. The text is set out in four parts as follows: PART 1, involving chapters 1 to 12, contains 'Basic Electrical Engineering Principles' which any student wishing to progress in electrical engineering would need to know. An introduction to electrical circuits, resistance variation, chemical effects of electricity, series and parallel circuits, capacitors and capacitance, magnetic circuits, electromagnetism, electromagnetic induction, electrical measuring instruments and measurements, semiconductor diodes and transistors are all included in this section. PART 2, involving chapters 13 to 22, contains 'Electrical Principles and Technology' suitable for Advanced GNVQ, National Certificate, National Diploma and City and Guilds courses in electrical and electronic engineering. D.c. circuit theory, alternating voltages and currents, single-phase series and parallel circuits, d.c. transients, operational amplifiers, three-phase systems, transformers, d.c. machines and threephase induction motors are all included in this section. PART 3, involving chapters 23 to 45, contains 'Advanced Circuit Theory and Technology' suitable for Degree, Higher National Certificate/Diploma and City and Guilds courses in electrical and electronic/telecommunications engineering. The two earlier sections of the book will provide a valuable reference/revision for students at this level. Complex numbers and their application to series and parallel networks, power in a.c. circuits, a.c. bridges, series and parallel resonance and Q-factor, network analysis involving Kirchhoff's laws, mesh and nodal analysis, the superposition theorem, Thévenin's and Norton's theorems, delta-star and star-delta transforms, maximum power transfer theorems and impedance matching, complex waveforms, harmonic analysis, magnetic materials, dielectrics and dielectric loss, field theory, attenuators, filter networks, magnetically coupled circuits, transmission line theory and transients and Laplace transforms are all included in this section. PART 4 provides a short, 'General Reference' for standard electrical quantities -their symbols and units, the Greek alphabet, common prefixes and resistor colour coding and ohmic values. At the beginning of each of the 45 chapters learning objectives are listed. At the end of each of the first three parts of the text is a handy reference of the main formulae used. xviii Electrical Circuit Theory and Technology It is not possible to acquire a thorough understanding of electrical principles, circuit theory and technology without working through a large number of numerical problems. It is for this reason that 'Electrical Circuit Theory and Technology, Revised second Edition' contains some 740 detailed worked problems, together with over 1100 further problems, all with answers in brackets immediately following each question. Over 1100 line diagrams further enhance the understanding of the theory. Fourteen Assignments have been included, interspersed within the text every few chapters. For example, Assignment 1 tests understanding of chapters 1 to 4, Assignment 2 tests understanding of chapters 5 to 7, Assignment 3 tests understanding of chapters 8 to 12, and so on. These Assignments do not have answers given since it is envisaged that lecturers could set the Assignments for students to attempt as part of their course structure. Lecturers' may obtain a complimentary set of solutions of the Assignments in an Instructor's Manual available from the publishers via the internet -see below. 'Learning by Example' is at the heart of 'Electrical Circuit Theory and Technology, Revised second Edition'.