ABSTRACT
In Europe and the UK, the units for measuring different properties are known as SI units.
SI stands for Syste`me Internationale.
All units are derived from seven base units.
Base quantity Base unit Symbol
Time Second s Electrical current Ampere A Length Metre m Mass Kilogram kg Temperature Kelvin K Luminous intensity Candela cd Amount of substance Mole mol
Derived quantity Name Symbol
Frequency Hertz Hz Force Newton N Energy, work, quantity of heat Joule J Electric charge, quantity of electricity
Coulomb C
Power Watt W Potential difference, electromotive force
Volt V or U
Capacitance Farad F Electrical resistance Ohm Magnetic flux Weber Wb Magnetic flux density Tesla T Inductance Henry H Luminous flux Lumen cd Area Square metre m2
Volume Cubic metre m3
Velocity, speed Metre per second m/s Mass density Kilogram per
cubic metre kg/m3
Luminance Candela per square metre
Name Multiplier Prefix Power of 10
Tera 1000 000 000 000 T 1× 1012 Giga 1000 000 000 G 1× 109 Mega 1000 000 M 1× 106 Kilo 1000 k 1× 103 Unit 1 Milli 0.001 m 1× 10−3 Micro 0.000 001 1× 10−6 Nano 0.000 000 001 1× 10−9 Pico 0.000 000 000 001 1× 10−12
mA Milliamp=one thousandth of an ampere km Kilometre = one thousand metres v Microvolt = one millionth of a volt GW Gigawatt = one thousand million watts kW Kilowatt = one thousand watts
Calculator example
1 kilometre is 1metre× 103 Enter into calculator 1 EXP 3= (1000) metres
1000metres is 1 kilometre× 10−3 Enter into calculator 1000 EXP −3 = (1) kilometre 1microvolt is 1 volt× 10−6 Enter into calculator 1 EXP −6 = (1−06 or 0.000 001) volts (note sixth decimal place).
