In this post, we will look at the book Units of Physical Quantities and their Dimensions by L. A. Sena.

**About the book**

The present book sets out in detail the principles of constructing systems of units, and also the fundamentals of the theory of dimensions. Together with detailed information on the SI system, which is the preferable one at present, a description is given of other systems of units, and also of some non-system units having practical significance.

The book is intended for students of technical colleges and will also be helpful for physics instructors in higher and secondary schools.

The book was translated from the Russian by G. Leib and was first published by Mir in 1972.

We were looking for this book for many years. Many thanks to **Hitesh** for the original scan of the book. We cleaned/OCRed/bookmarked the 2-in-1 scan.

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**CONTENTS**

Foreword 7

Chapter One. General Concepts on Systems of Basic and Derived Units 11

1.1. Physical Quantities and Their Units 11

1.2. Direct and Indirect Measurements 16

1.3. Basic and Derived Units 18

1.4. Constructing a System of Units 24

1.5. Selection of Basic Units 34

1.6. Non-System Units 40

Chapter Two. Conversion of Units and Dimension Formulas 42

2.1. Dimension Formulas 42

2.2. Conversion of Dimension When Using Different Basic Units 47

2.3. Conversion of Dimensions with Different Defining Relationships 48

2.4. Determining the Relationship between Units of Different Systems 52

2.5. Compilation of Conversion Tables 58

2.6. On the So-called Meaning of Dimension Formulas 59

2.7. Brief Conclusions on Chapters One and Two 62

Chapter Three. Analysis of Dimensions 65

3.1. Determining Functional Relationships by Comparing Dimensions 65

3.2. The II-Theorem and the Method of Similarity 72

Chapter Four. Units of Geometrical and Mechanical Quantities 79

4.1. Introduction 79

4.2. Geometrical Units 80

4.3. Kinematic Units 91

4.4. Static and Dynamic Units 96

4.5. Units of Mechanical and Molecular Properties of a Substance 109

Chapter Five. Thermal Units 121

5.1. Temperature 121

5.2. Temperature Scales 128

5.3. Fixed Temperature Points 130

5.4. Other Thermal Units 130

5.5. Units of Thermal Properties of Substances 135

Chapter Six. Acoustic Units 142

6.1. Objective Characteristics of Mechanical Wave Processes 142

6.2. Subjective Characteristics of Sound 147

6.3. Some Quantities Connected with the Acoustics of Buildings 150

Chapter Seven. Electrical and Magnetic Units 153

7.1. Introduction 153

7.2. Possible Ways of Constructing Systems of Electrical and Magnetic Units 154

7.3. Units of theCGS System 169

7.4. Units of the SI System 182

7.5. On the So-called Wave Resistance of a Vacuum 196

7.6. International Units 198

Chapter Eight. Units of Radiation 201

8.1. Scale of Electromagnetic Waves 201

8.2. Characteristics of Radiant Energy 202

8.3. Illumination Engineering Units 207

8.4. Relationship between Subjective and Objective Characteristics of Light 212

8.5. Units of Parameters of Optical Instruments 214

8.6. Units of Optical Properties of a Substance 217

Chapter Nine. Selected Units of Atomic Physics 218

9.1. Introduction 218

9.2. Basic Properties of Atomic and Elementary Particles 218

9.3. Effective Interaction Cross Sections 223

9.4. Units of Energy in Atomic Physics 225

9.5. Ionizing Radiation Units 229

9.6. Units of Radioactivity 231

9.7. Ionization, Recombination and Mobility Coefficients 233

9.8. Natural Systems of Units 235

Appendix 1. Logarithmic Units 238

Appendix 2. Measuring the Density of a Liquid with an Areo meter 241

Appendix 3. pH Index 242

Appendix 4. Constants 243

Appendix 5. Tables 245

Bibliography 286

Index 288