UNITS OF MEASUREMENT

In this post, we use base units which have been established in The 14th General Conference on Weights and Measures (1971). The base measurement system is known as SI which stands for French “Le Systéme International d’Unités” (Table 1). All other physical quantities are derivatives of these base units.

Tabel 1. SI Basic Units

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. When pronounced, in all cases the first syllable is accented. For example, 1 ampere (A) may be multiplied by factor of 10-3 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, 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.