SYSTEM OF UNITS

System of Units

We all electrical engineers deals with several measurable quantities. However, our measurement must be communicated in standard language such that an engineering professional can understand, irrespective of the country where the measurement is conducted.

Such an international measurement language is the International System of Units (SI), adopted by the General Conference on weights and measures in 1960. In this international system there are six principle units from which the units of all the other physical quantities can be obtained. One major advantage of the SI unit is that it uses prefixes based on the power of 10 to relate smaller and larger units to the basic unit.

Quantity	Basic Unit	Symbol
Luminous Intensity	Candela	Cd
Thermodynamics Temperature	Kelvin	K
Length	Meter	m
Mass	Kilogram	Kg
Time	Second	s
Electric Current	Ampere	A

The SI unit Prefix are: -

Multiplier	Prefix	Symbol
1018	exa	E
1015	penta	P
1012	tera	T
109	giga	G
106	mega	M
103	kilo	K
102	hecto	H
10	deka	da
10-1	deci	d
10-2	centi	c
10-3	milli	m
10-6	micro	µ
10-9	nano	n
10-12	pico	p
10-15	femto	f
10-18	atto	a