In this book, we use base units which have been established in The 14th General Conference onWeights and Measures (1971). The base measurement system is known as SI which stands for French “Le Systéme International d’Unités” (Table 1.7) [4]. All other physical quantities are derivatives of these base units. Some of them are listed in Table A.3.
Often, it is not convenient to use base or derivative units directly; in practice, quantities may be either too large or too small. For convenience in the engineering work, multiples and submultiples of the units are generally employed. They can be obtained by multiplying a unit by a factor from Table A.2. When pronounced, in all cases the first syllable is accented. For example, 1 ampere (A) may be multiplied by factor of 0.001 to obtain a smaller unit: 1 milliampere (mA), which is one-thousandth of an ampere.
Sometimes, two other systems of units are used. They are the Gaussian System and the British System, which in the United States its modification is called the U.S. Customary System. The United States is the only developed country in which SI
Often, it is not convenient to use base or derivative units directly; in practice, quantities may be either too large or too small. For convenience in the engineering work, multiples and submultiples of the units are generally employed. They can be obtained by multiplying a unit by a factor from Table A.2. When pronounced, in all cases the first syllable is accented. For example, 1 ampere (A) may be multiplied by factor of 0.001 to obtain a smaller unit: 1 milliampere (mA), which is one-thousandth of an ampere.
Sometimes, two other systems of units are used. They are the Gaussian System and the British System, which in the United States its modification is called the U.S. Customary System. The United States is the only developed country in which SI
still is not in common use. However, with the end of communism and the increase of world integration, international cooperation gains strong momentum. Hence, it is unavoidable that the United States will convert to SI in the future, although maybe not in our lifetime. Still, in this book, we will generally use SI; however, for the convenience of the reader, the U.S. customary system units will be used in places where U.S. manufacturers employ them for sensor specifications. For the conversion to SI from other systems, the reader may use Tables A.4. To make a conversion, a
The reader should consider the correct terminology of the physical and technical terms. For example, in the United States and many other countries, the electric potential difference is called “voltage,” whereas in other countries, “electric tension” or simply “tension” is in common use. In this book, we use terminology that is traditional in the United States.
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