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Units and Measurements — Revision Notes

CBSE · Class 11 · Physics

Units and Measurements revision notes for CBSE Class 11 Physics: 4 topics in quick points. Part of the CBSE Class 11 Physics syllabus.

147 questions72 flashcards5 concepts

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Key Topics to Revise

1

1. Physical Quantities, Units, and Systems of Units

  • A physical quantity is expressed as a numerical value and a unit.
  • Measurement involves comparison with a basic, arbitrarily chosen, internationally accepted reference standard called a unit.
  • Fundamental or base quantities are independent quantities used to define other quantities.
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2. SI Base Units and Retained Units

  • The seven SI base quantities are length, mass, time, electric current, thermodynamic temperature, amount of substance, and luminous intensity.
  • The SI base units are metre, kilogram, second, ampere, kelvin, mole, and candela.
  • The metre is defined using the fixed numerical value of the speed of light in vacuum c.
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3. Significant Figures and Scientific Notation

  • Significant figures show the precision of a measurement.
  • All non-zero digits are significant.
  • Zeros between two non-zero digits are significant.
4

4. Rules for Rounding Off and Error Handling

  • If the digit to be dropped is less than 5, the previous digit stays the same.
  • If the digit to be dropped is more than 5, the previous digit increases by 1.
  • If the dropped digit is exactly 5, the previous digit is kept unchanged if it is even and increased by 1 if it is odd.

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Full Notes

Key Concepts

Measurement of any physical quantity involvesThe fundamental or base quantitiesQuantities obtained from base quantitiesThe SI system is the internationallyRadian and steradian are dimensionless SI

Frequently Asked Questions

What are the important topics in Units and Measurements for CBSE Class 11 Physics?
Key topics in Units and Measurements include Physical Quantities, Units, and Systems of Units, SI Base Units and Retained Units, Significant Figures and Scientific Notation, Rules for Rounding Off and Error Handling. Study these first, then practise questions on each for Class 11 exams.
How should I revise Units and Measurements for Class 11 exams?
Learn the core ideas first, then work through the 147 practice questions on Units and Measurements. Revise definitions regularly and use flashcards for quick recall before the exam.

Sources & Official References

Content is aligned to the official syllabus. Refer to the board website for the latest curriculum.

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All CBSE Class 11 Physics Revision Notes

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