Physics is an exact science which gives an accurate knowledge about the nature and the natural phenomena. It expresses various natural phenomena in terms of the relationships among the quantities involved. The exactness or accuracy of these relationships depends upon the measurements we make. The accuracy of the measurements, in turn, depends on the accuracy of the measuring instruments and techniques. The recent progress in science and technology has been possible only due to the development of high precision instruments. One can measure mass as small as that of an electron (-10-30 kg) and as large as that of the universe (-1055 kg).
Prof. William S. Franklin emphasized the importance of measurement in the following words:
“The most important thing for a young man to acquire from his first course in physics is an appreciation for precise details.”
Stressing upon the importance of measurement, Lord Kelvin, a great English physicist of 19th century, once remarked that
“When you can measure what you are speaking about and express it in numbers, you know something about it, but when you cannot measure it and express it in numbers, your knowledge is of a meagre and unsatisfactory kind, but you have scarcely, in your thoughts, advanced to the stage of science whatever the matter may be.”