Rev. Notes > AS > Physical quantities and units Previous Topic Physical quantities and units Next Topic Topics
 Physics Areas of Physics Interdisciplanary areas of physics Quantities in Physics Base Units Convention for indicating units Derived Units S.I. Units (International System of Units) Supplementary units Homogeneity of equations Significant figures Rules of Significant figures Further discussion on Significant figures Dimensions Scientific notation The Avogadro's Constant Scalars and Vectors Addition and subtraction of co-planar vectors Rectangular components of a vector

## S.I. Units (International System of Units)

In 1960, an international committee agreed on a set of definitions and standard to describe the physical quantities. The system that was established is called the system international (SI).

Due to the simplicity and convenience with which the units in this system are amendable to arithmetical manipulation, it is in universal use by the world’s scientific community and by most nations. The system international (SI) is built up from three kinds of units: base units, Supplementary units and derived units.

S.I. Base Units

 Base Quantity Name Symbol Length meter m Mass kilogram kg Time seconds s Electric current ampere A Tempearture kelvin k Amount of substance mole mol Luminous intensity candela cd

S.I. Derived Units

 Derived Quantity Name Symbol Equivalent S.I. Units Frequency hertz Hz S-1 Force newton N m.Kg.S-2 Pressure pascal Pa N.m-2 Energy joule J N.m Power watt W Js-1 Electric charge coulomb C A.s Electric potential volt V W.A-1 Electric resistance ohm Ω V.A-1 Temperature degree celsius oC k

S.I. Prefixes

 Name Factor Symbol Numerical value tera 1012 T 1 000 000 000 000 giga 109 G 1 000 000 000 mega 106 M 1 000 000 kilo 103 k 1 000 hecto 102 h 1 00 deka 101 da 10 deci 10-1 d 0.1 centi 10-2 c 0.01 milli 10-3 m 0.001 micro 10-6 µ 0.000 001 nano 10-9 n 0.000 000 001 pico 10-12 p 0.000 000 000 001

 Add Comment | FAQs | Report Error | | |

View Comments on this Chapter - Total Comments (4)

 Student Said : Super i got so much of information through physicsatweb.com 11/07/15 09:09 AM

 Kennyworthy Mphande Said : nicely explained. 26/01/15 07:00 PM

 benard wilson Said : very good notes and easy to understand. i wish u can make more of dem 10/09/14 09:57 PM

 muhammad fawad Said : nice writting.. 06/05/14 06:47 PM

# About us:

A team of committed professionals providing free online resources of physics for the learners of IGCSE/AS/ A Level .....