This book delivers a comprehensive overview of units of measurement. Beginning with a historical look at metrology in Ancient India, the book explains fundamental concepts in metrology such as basic, derived and dimensionless quantities, and introduces the concept of quantity calculus. It discusses and critically examines various three and four-dimensional systems of units used both presently and in the past, while explaining why only four base units are needed for a system of measurement. It discusses the Metre Convention as well as the creation of the International Bureau of Weights and Measures, and gives a detailed look at the evolution of the current SI base units of time, length, mass, electric current, temperature, intensity of illumination and substance.

This updated second edition is extended with timely new chapters discussing past efforts to redefine the SI base units as well as the most recent 2019 redefinitions based entirely on the speed of light and other fundamental physical constants. Additionally, it provides biographical presentations of many of the historical figures behind commonly used units of measurements, such as Newton, Joule and Ohm, With its accessible and comprehensive treatment of the field, together with its unique presentation of the underlying history, this book is well suited to any student and researcher interested in the practical and historical aspects of the field of metrology.

Autorentext

Dr. S. V. Gupta received master's degrees in physics and mathematics from Allahabad University and Agra University, India, respectively, and holds a PhD from Delhi University. Dr. Gupta subsequently completed advanced training at the International Bureau of Weights and Measures, BIPM, France; International Organisation of Legal Metrology (OIML), Paris France; National Physical Laboratory, UK; and PTB (Physikalisch-Technische Bundesanstalt), Germany. He has been involved in various projects with the National Institute for Standards and Technology, NIST, USA and with the PTB, Germany. Dr. Gupta was recently awarded the title of Mapiki Ratan (a Jewel in Metrology). He is a member of the Institute of Physics UK. He is first Asian whose name has been placed in the Honours and awards list of the International Organisation of Legal Metrology (OIML), Paris, France since 2004. He has worked in the National Physical Laboratory of India for 37 years. He has been UNIDO Expert to various countries. After retirement from the regular service, he has written about 23 books (including editions) on different topics of metrology and legal metrology.

Zusammenfassung

It is for the first time that the subject of quantities and their respective units is dealt this much in detail, a glimpse of units of measurements of base quantities of length, time, mass and volume is given for ancient India, three and four dimensional systems of measurement units are critically examined, establishment of the fact that only four base units are needed to describe a system of units, the basics to arrive at the unit of a derived quantity are explained, basic, derived and dimensionless quantities including quantity calculus are introduced, life history of scientists concerned with measurements units are presented to be inspiring to working metrologists and students. The International System of Units including, Metre Convention Treaty and its various organs including International National of Weights and Measure are described. The realisation of base units is given in detail. Classes of derived units within the SI, units permitted for time to come, units outside SI but used in special fields of measurements are described. Methods to express large numbers are explained in detail. Multiples and sub-multiples prefixes and their proper use are also given. The latest trends to redefine the base Kilogram, Ampere, Kelvin and Mole on existing base units of mass, electric current, temperature and amount of substance, in terms of a single parameter or fundamental constants are briefly described.

Inhalt

Metrology Through the Ages.- System of Quantities and Units.- Various Systems of Units.- Metre Convention and Evolution of Base Units.- BIPM and Metre Convention.- New Definitions SI Base Units.- Realization of the SI Base units (s, m, kilogram).- Realization of SI Base Unit Ampere and Other Electric Units in the SI.- Boltzmann Constant Defining Kelvin K.- Radiometry, Photometry & Realization of Candela and Mole.- Derived Quantities and Their Units.- Expressing SI Units.- Past Efforts in Redefining SI Units.- Scientists Associated with Units of Measurements.