Importance of Unit System in Science
In science, mere qualification of a parameter is not enough. In almost every cases the quantification is a necessity. And as far quantification is concerned, units are absolutely necessary to express a quantity. For example if we say that 100 force, it does not really carry any meaning. When we say a 100kg or 1000 newton force is acting, it becomes meaningful and concerned people get to understand the amount of force which is in action. So it is kind of needless to emphasize the importance of units while expressing a parameter. But is has been seen than many a science grads take it lightly and make huge mistakes while dealing with scientific parameters. Without clear conception of unit system one can not solve problems when units are involved in a problem. It’s not that the concepts of units are too complicated and difficult to conceive. But initial ignorance or maybe lack of proper teaching are the reasons for being weak in understanding units.
Here in this tutorial a recapitulation of the same old concepts of unit system is being done. It may clear your confusions and make you stronger in understanding and solving scientific problems. We shall be going over the subjects briefly with the aim of strengthening the fundamentals so that there are no chances of faltering anywhere.The age old British system of units , in which the basic units of length, mass and time are foot, pound and second respectively, is an almost forgotten system now. It need not be touched here. The system was replaced by C.G.S system. Then came the M.K.S System and now we follow the S.I system of units.
In C.G.S system C stands for centimeter (unit of length), G stands for gram (unit of mass) and S for second (Unit of time). Unit of these three physical quantity length, mass and time are known as fundamental units. All other units of various quantities will be derived units.
But with development of science and technology and introduction of electromagnetic theory, this system was found to be having certain deficiencies. In 1904 prof. Giorgi of Rome suggested the use of M.K.S (Meter, Kilogram, Second) system which removed many of the difficulties faced by the C.G.S system.
In the year 1960, the international standards Organization held a conference of leading countries of the world. By adding definitions of units electric current (ampere), thermodynamic temperature (Kelvin), and luminous intensity (candela)to the basic units Meter-Kilogram-Second of the M.K.S system, a new system of units was adopted which is known as the Systeme Internationale d’ Units (International System of Units), abbreviated as S.I units. This is the system to which all the countries of the world are now switching over.
Primary and derived units of S.I. System
In S.I unit there are seven primary units as follows
Quantity Unit Symbol
Length meter m
Mass Kilogram kg
Time second s
Electric Current ampere a
Temperature Kelvin K
Luminous Intensity candela cd
Amount of substance mole mol
A derived unit is one which can be expressed in terms of one or more primary units. Square meter (m2) is a derived unit of area because it expresses area in terms of primary unit meter (m).
