NCERT Solutions for Class 11 Physics Chapter 2 Units and Measurement


NCERT Solutions for Class 11 Physics Chapter 2 Units and Measurement: Measurements are always specified with a unit. Without units, measurement is meaningless. For example, a man tells the distance between my home and the nearest city is 5. This statement by the man is meaningless. Whether it is 5m, 5cm or 5Km makes it meaning full. The NCERT Solution for Class 11 Physics Chapter 2 starts with the definition of units and what is the relationship between units and measurements. Now let’s take an example: The actual measurement of the length of a table is 1.5 meter. By using a meter scale a person finds the measurement to be 1.4 m and with a centimeter scale, he finds the measurement to be 136cm= 1.36m. Here the first reading is said to be more accurate than second reading and the second reading is said to be more precise than the first reading. And this difference in the value of reading from true value is the error in measurement. The concept of accuracy, precision and error is well defined in the NCERT Solutions for Class 11 Physics Chapter 2 Units and Measurement:

The main headings and subheadings of the NCERT Solution for Class 11 Physics Chapter 2 are listed below.

2.1 Introduction

2.2 The International System Of Units

2.3 Measurement Of Length

2.3.1 Measurement Of Large Distances

2.3.2 Estimation Of Very Small Distances

2.3.3 Range Of Lengths

2.4 Measurement Of Mass

2.4.1 Range Of Masses

2.5 Measurement Of Time

2.6 Accuracy, Precision Of Instruments And Errors In Measurement

2.6.1 Absolute Error, Relative Error And Percentage Error

2.6.2 Combination Of Errors

2.7 Significant Figures

2.7.1 Rules For Arithmetic Operations With Significant Figures

2.7.2 Rounding Off The Uncertain Digits

2.7.3 Rules For Determining The Uncertainty In The Results Of Arithmetic Calculation

2.8 Dimensions Of Physical Quantities

2.9 Dimensional Formulae And Dimensional Equations

2.10 Dimensional Analysis And Its Applications

2.10.1 Checking The Dimensional Consistency Of Equation

2.10.2 Deducing Relation Among The Physical Quantities

The important topics of NCERT Solution for Class 11 Physics Chapter 2 are errors and measurement of errors, dimensional analysis and significant figures. This is an easy and important chapter in the board exam and competitive exam point of view.

Let’s take an example to understand the concept of dimensional consistency mentioned in the NCERT Class 11 Chapter 2 Units and Measurement. You have studied the equation’s of uniform motion in your high school classes. The relation between initial velocity u, final velocity v, acceleration a and time t is given by v=u+at, which is dimensionally correct. Now let's consider v=u+0.5at. Is it dimensionally right? The dimension of v=u and dimension of at =  dimension of v and 0.5 is dimensionless, so the equation v=u+0.5at is dimensionally right but it is not the actual equation. Now consider the equation v=ut+at, which is dimensionally incorrect and the relation is also incorrect. This shows that if an equation is dimensionally correct does not imply that the equation is right. If the equation is dimensionally wrong implies that the equation is definitely wrong.

The complete NCERT Solution for Class 11 Physics Chapter 2 is given below:

Q-2.1 Fill in the blanks: (a) The volume of a cube of side 1 cm is equal to .....m3 (b) The surface area of a solid cylinder of radius 2.0 cm and height 10.0 cm is equal to ...

View all NCERT Solutions for Class 11 Physics Chapter 2 Units and Measurement here

NCERT Solutions for class 11 Physics


Physical world


Motion in a straight line


Motion in a Plane


Laws of Motion


Work, Energy and Power


System of Particles and Rotational motion




Mechanical Properties of Solids


Mechanical Properties of Fluids


Thermal Properties of Matter




Kinetic Theory





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