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# NCERT Solutions for Class 11 Physics Chapter 2 – Units and Measurement

NCERT Solutions for Class 11 Physics Chapter 2 should be your first choice if you want to get a basic understanding of Units and Measurement. Chapter 2 is definitely one of the most fundamental chapters of Physics. Apart from learning about the units of physical quantities and discussing the methods of evaluating these units, this chapter also covers the concept of errors that might occur while taking measurements.

The chapter includes 2 exercises with 33 questions that are comprehensively covered in our solutions. These questions will test your ability to measure time, mass, length etc. The NCERT solutions are presented in a step-by-step manner so that you know exactly how to solve the numerical related to measurement effectively in your CBSE Physics exams.

While revising Chapter 2 of NCERT Physics Textbook for Class 11, you must go through the questions given at the end to anticipate the kind of questions you will be asked. With the help of NCERT solutions by Instasolv, you will be able to revise the chapter conveniently, get accustomed to the question patterns and ultimately score a good percentile as well.

## Important Topics for NCERT Solutions for Class 11 Physics Chapter 2

Units and Measurement is a scoring chapter of the physics syllabus only if you learn the important points efficiently. So, let us go through some of the essential topics that are covered in NCERT Class 11 Physics Chapter 2- Units and Measurement, for your convenience.

System of Units

Unit is basically a standard used for measuring the quantities and it is usually internationally accepted. Fundamental units are those which are used for the base quantities like time, length, while derived units are the combination of fundamental units. Together, fundamental and derived units create a system of units.

International System of Units

The seven base units which you should be aware of as these are internationally accepted are the following:

1. Length- Metre
2. Mass- Kilogram
3. Time-Second
4. Electric Current- Ampere
5. Thermodynamic Temperature- Kelvin
6. Amount of Substance- Mole
7. Luminous Intensity- Candela

Parallex Method

This method is used to measure the long distances especially the distance of a planet. It is basically the difference in the position of an object which is viewed from two different viewpoints and is measured by the angle of inclination between those two viewpoints.

Electron Microscopes

Very small distances like the size of molecules or atoms are measured with the help of electron microscopes that contain the beams of electrons controlled by magnetic and electric fields.

### Important Highlights Associated with Measurement

Measurement of Mass: Kilogram, the unit to measure mass but Unified Atomic Mass Unit (U) is the unit to measure molecules and atoms. Balances are used to measure the normal weights, whereas gravitational methods are used to measure the mass of planets. Some common range of mass:

• Electron- 1030
• Proton- 10-27
• Moon-1021
• Earth-1025
• Sun-1030

Measurement of Time: The clock is used for measuring time. Atomic standard time measured with the help of caesium clock also known as the atomic clock is used in which vibrations of caesium atom help determine the time. Some common time intervals:

• Period of lightwave: 10-15
• Period of a sound wave: 10-3
• Travel time of moonlight to Earth: 100

Measurement of Length: Speedometer (10-5 m), screw gauge, Vernier callipers and meter scale is used to measure length. Some common range of length:

• The thickness of the paper: 10-4
• The radius of the earth: 107
• The distance of the moon from the sun: 108
• The distance of the sun from the earth: 1011

Types of Errors

During measurement, there is a high possibility of errors. These are some of the errors covered in Chapter 2 of NCERT Physics Textbook in details:

• The systematic error occurs due to instrument errors, an imperfection in techniques of experiments and personal errors;
• Another kind of error is random errors which occur because of unpredictable changes in a situation like temperature changes, fluctuation of voltage etc.
• Least count error which is an error related to least count or resolution of the measuring instrument.
• Absolute error, mean absolute error, relative error, percentage error are other errors dealt with in the chapter.

Dimensional Formula

• Volume: [M0 L3 T0
• Speed: [M0 L T-1]
• Force: [M L T-2
• Density: [M L-3 T0]

### Discussion of Questions of NCERT Solutions for Class 11 Physics Chapter 2

• Chapter 2 of NCERT textbook for Class 11 Physics has 33 questions.
• There are questions which help you practice conversion of units as well as revise theoretical concepts which have been discussed in the chapter.
• Some questions deal exclusively with finding the significant figures in certain given numbers or given conditions.
• A majority of the questions from the 33 questions deal with numerical which allow you to find the diameter of the moon/any planet, the distance between objects, the mass density of objects etc.

### Benefits of NCERT Solutions for Class 11 Physics Chapter 2 by Instasolv

The NCERT Solutions for Class 11 Physics Chapter 2 are created meticulously by our subject matter experts. Refer to our solutions once and we guarantee that you will be able to grasp all the concepts well. Step-wise solutions, clear explanations and diagrams are some of the top-notch features of our NCERT solutions.

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