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# UNITS AND MEASUREMENTS

UNITS AND MEASUREMENTS is chapter 1 in Physics Part - I, a CBSE Class 11 book for the subject Physics on Edzy.

## Knowledge Snapshot

| Field | Details |
| :--- | :--- |
| Board | CBSE |
| Curriculum | CBSE |
| Class | Class 11 |
| Subject | Physics |
| Book | Physics Part - I |
| Chapter | UNITS AND MEASUREMENTS |
| Chapter Number In Book | 1 |
| Chapter Slug | units-and-measurements |
| Pages | 1-12 |
| Page Count | 12 |
| Source PDF | https://edzy-ai.s3.ap-south-1.amazonaws.com/edzy-express-ts/c8e64e9d-6bb8-4b72-a817-e9aad5ec49a5.pdf |
| Last Updated | 2026-06-25 |

## Chapter Overview

This chapter introduces the concept of measurement of physical quantities, the International System of Units (SI), significant figures, dimensions of physical quantities, dimensional formulas and equations, and the applications of dimensional analysis. The overarching aim is to establish a clear understanding of how these concepts interrelate and contribute to accurate scientific measurement and analysis.

## Topic Inventory

| No. | Topic ID | Topic |
| :--- | :--- | :--- |
| 1 | 69abcf8ba243cecf9685e771 | INTRODUCTION |
| 2 | 69abcf8ba243cecf9685e773 | THE INTERNATIONAL SYSTEM OF UNITS |
| 3 | 69abcf8ba243cecf9685e775 | SIGNIFICANT FIGURES |
| 4 | 69abcf8ba243cecf9685e777 | DIMENSIONS OF PHYSICAL QUANTITIES |
| 5 | 69abcf8ba243cecf9685e779 | DIMENSIONAL FORMULAE AND DIMENSIONAL EQUATIONS |
| 6 | 69abcf8ba243cecf9685e77b | DIMENSIONAL ANALYSIS AND ITS APPLICATIONS |

## Topic-Wise Extracted Content

### INTRODUCTION
Measurement of any physical quantity involves comparison with a certain basic, arbitrarily chosen, internationally accepted reference standard called unit. The result of a measurement is expressed by a number accompanied by a unit. We need only a limited number of units for expressing all physical quantities since they are interrelated. The units for fundamental quantities are termed as fundamental or base units, while units of other quantities can be expressed as combinations of base units, called derived units.

### THE INTERNATIONAL SYSTEM OF UNITS
The internationally accepted system of measurement is the Système Internationale d’Unites (SI). Earlier, different countries used various systems such as CGS, FPS, and MKS. SI has seven base units and two additional units for plane and solid angles, called radian (rad) and steradian (sr) respectively. A significant feature of SI units is their decimal system, making conversions straightforward.

### SIGNIFICANT FIGURES
Measurements inherently involve errors; hence reported measurements should indicate precision. Significant figures are the known digits in a measurement plus the first uncertain digit. Rules for significant figures include: all non-zero digits are significant, zeros between significant digits are significant, and trailing zeros in decimal numbers are significant.

### DIMENSIONS OF PHYSICAL QUANTITIES
The dimensions of a physical quantity define it. Physical quantities can be expressed in terms of seven base quantities: length [L], mass [M], time [T], electric current [A], thermodynamic temperature [K], luminous intensity [cd], and amount of substance [mol]. For instance, the volume of an object can be expressed as [L]³.

### DIMENSIONAL FORMULAE AND DIMENSIONAL EQUATIONS
The dimensional formula indicates the relationship between a physical quantity and base quantities. For example, the dimensional formula for speed is [M⁰ L T⁻¹]. Dimensional equations equate a physical quantity with its dimensional formula.

### DIMENSIONAL ANALYSIS AND ITS APPLICATIONS
Dimensional analysis allows for confirming the consistency of equations. Only quantities with similar dimensions can be added or subtracted. It is essential to ensure that all terms in an equation have the same dimensions to verify correctness.

## Chapter Summary

The chapter on Units and Measurements lays the foundation for understanding the measurement system used in physics, encompassing base and derived units, significant figures, dimensions, and the utility of dimensional analysis in ensuring the consistency of mathematical expressions.

## Key Ideas

- Measurement is vital for comparing physical quantities using reference standards or units.
- The SI system is the international standard for measurements.
- Significant figures convey the precision of measurements.
- Dimensions relate physical quantities to their fundamental bases.
- Dimensional analysis is crucial for testing the validity of physical equations.

## Important Chapter Facts

- The chapter is UNITS AND MEASUREMENTS.
- The chapter number in the book is 1.
- The subject is Physics.
- The book is Physics Part - I.
- The class is Class 11.
- The source PDF is https://edzy-ai.s3.ap-south-1.amazonaws.com/edzy-express-ts/c8e64e9d-6bb8-4b72-a817-e9aad5ec49a5.pdf.
- The chapter covers pages 1-12.
- The chapter page count is 12.
- The topic list contains the supplied topic entries.

## Related OKF Entities

| Entity Type | Title | URL |
| :--- | :--- | :--- |
| Chapter Canonical Page | UNITS AND MEASUREMENTS | https://www.edzy.ai/cbse-class-11-physics-physics-part-i-units-and-measurements |
| Chapter Markdown | UNITS AND MEASUREMENTS | https://www.edzy.ai/okf/chapter/cbse-class-11-physics-physics-part-i-units-and-measurements.md |
| Source PDF | UNITS AND MEASUREMENTS | https://edzy-ai.s3.ap-south-1.amazonaws.com/edzy-express-ts/c8e64e9d-6bb8-4b72-a817-e9aad5ec49a5.pdf |

## Source Attribution

| Field | Value |
| :--- | :--- |
| Source | Edzy |
| Reference Type | examSubjectBookChapter |
| Reference ID | 66f15a53e361cd99fe37113a |
| Chapter ID | 66f15a53e361cd99fe37113a |
| Canonical URL | https://www.edzy.ai/cbse-class-11-physics-physics-part-i-units-and-measurements |
| Markdown URL | https://www.edzy.ai/okf/chapter/cbse-class-11-physics-physics-part-i-units-and-measurements.md |
| Source PDF | https://edzy-ai.s3.ap-south-1.amazonaws.com/edzy-express-ts/c8e64e9d-6bb8-4b72-a817-e9aad5ec49a5.pdf |
| Last Updated | 2026-06-25 |