Chapter Two
Units and Measurement
2.1 Introduction
2.2 The international system of units
2.3 Measurement of length
2.4 Measurement of mass
2.5 Measurement of time
2.6 Accuracy, precision of instruments and errors in measurement
2.7 Significant figures
2.8 Dimensions of physical quantities
2.9 Dimensional formulae and dimensional equations
2.10 Dimensional analysis and its applications
Summary
Exercises
Additional exercises
2.1 Introduction
NEETprep Audio Note:
Measurement of any physical quantity involves comparison with a certain basic, arbitrarily chosen, internationally accepted reference standard called unit. The result of a measurement of a physical quantity is expressed by a number (or numerical measure) accompanied by a unit. Although the number of physical quantities appears to be very large, we need only a limited number of units for expressing all the physical quantities, since they are inter-related with one another. The units for the fundamental or base quantities are called fundamental or base units. The units of all other physical quantities can be expressed as combinations of the base units. Such units obtained for the derived quantities are called derived units. A complete set of these units, both the base units and derived units, is known as the system of units.