2. Unit and measurement

● UNITS & QUANTITIES 

Physics describes the laws of nature. This description is quantitative and involves measurement and comparison of physical quantities. To measure a physical quantity we need some standard unit of that quantity.

 We can define a set of fundamental 
quantities as follows : 
(a) The fundamental quantities should be indepen￾dent of each other, and 
(b) All other quantities may be expressed in terms 
of the fundamental quantities. 

Quantity	Name of unit	symbol
Mass	kilogram	k
Length	metre	m
Time	second	s
Current	ampere	A
Amount of substance	mole	mol
Temperature	Kelvin	K
Intensity	candela	cd