Standards of Measurement

A standard is physical representation of a unit of measurement. A known accurate measure of physical quantity is termed as a standard. These standards are used to determine the value of other physical quantities by the comparison method.

A unit is realized by reference to a material standard or to natural phenomena, including physical and atomic constants. For example, the fundamental unit of length in the international system (SI) is the meter, defined as the distance between two fine lines engraved on gold plugs near the ends of a platinum-iridium alloy at 0⁰C and mechanically supported in a prescribed manner.

Similarly, different standards have been developed for other units of measurement (including fundamental units as well as derived mechanical and electrical units). All these standards are preserved at the International Bureau of Weight and Measures at Served, Paris.

Depending on the functions and applications, different types of Standards of Measurement are classified in below categories:-

1- International Standards

2- Primary Standards

3- Secondary Standards

4- Working Standards

5- Atomic Frequency & Time Standards

6- Electrical Standards