Class notes Physics Physics : Textbook For Class Xii

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KENDRIYA VIDYALAYA SANGHATHAN

CHANDIGARH REGION

CLASS-XI

SUBJECT-PHYSICS




Chapter -2

Units and Measurement




INDEX

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S. No. CONTENT P. No.

1 Gist of the Chapter and Formulae Used 3-7

2 Multiple Choice Questions 8-13
3 Assertion Reasoning Questions 14-15
4 Case Study Based Questions 16-19

5 Answer key 20

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GIST OF THE CHAPTER AND FORMULAE USED
 Physical quantity
 Fundamental and derived units
o S.I. units
o Dimensions
 Application of Dimensional Analysis
o Limitations of Dimensional Analysis
 Rounding off
 Significant Figures
 Order of Magnitude
 Errors of Measurement
 Propagation of Errors.



 PHYSICAL QUANTITY
A quantity which can be measured and expressed in form of law is called a physical quantity.

Physical quantity (Q) = Magnitude x units = n x u

Where

n= numerical value,

u= unit

As the unit (u) changes, magnitude (n) will also change but product ‘nu’ will remain same.

i.e. nu = constant, or n1u1 = n2u2



 S.I. system
It is known as international system of units. There are seven fundamental quantities in this
system.