SI Prefixes and Their Symbols

Topic Content:

The International System of Units:

The International System of Units , abbreviated as SI , is the internationally accepted system of units used for scientific measurements.

We have already seen that physical quantities are expressed using units. For example, the SI unit of length is the metre, the SI unit of mass is the kilogram, and the SI unit of time is the second.

SI units provide a common standard so that measurements can be understood and compared easily.

However, the basic SI unit is not always the most convenient unit for expressing a measurement.

For example:

• A distance of 5,000  m can be written more conveniently as 5  km.
• A length of 0.001  m can be written as 1  mm.

The symbols k in kilometre and m in millimetre are associated with SI prefixes . Since SI prefixes are based on powers of ten, our understanding