Physics: Units of Measurement
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Questions and Answers

What is the unit for plane angle?

  • Metre
  • Kilogram
  • Radian (correct)
  • Steradian

    • What is the unit for solid angle?

  • Radian
  • Steradian (correct)
  • Kilogram
  • Metre

    • Which of the following units are dimensionless quantities?

  • Kilogram and Second
  • Metre and Second
  • Radian and Steradian (correct)
  • Metre and Kilogram

    • What is the definition of the metre in terms of?

    <p>Speed of light in vacuum</p> Signup and view all the answers

    What is the definition of the kilogram in terms of?

    <p>Planck constant</p> Signup and view all the answers

    What is the definition of the second in terms of?

    <p>Caesium frequency</p> Signup and view all the answers

    What is the unit of the speed of light in vacuum?

    <p>m/s</p> Signup and view all the answers

    What is the term used to describe the units of physical quantities that are derived from the base units?

    <p>Derived units</p> Signup and view all the answers

    What is the purpose of a unit in measurement?

    <p>To compare the physical quantity with a reference standard</p> Signup and view all the answers

    What is the unit of the Planck constant?

    <p>J s</p> Signup and view all the answers

    Which of the following systems of units was extensively used in the past?

    <p>All of the above</p> Signup and view all the answers

    What is the term used to describe the process of expressing the units of physical quantities as combinations of base units?

    <p>Dimensional formulae</p> Signup and view all the answers

    What is the term used to describe the set of base units and derived units?

    <p>System of units</p> Signup and view all the answers

    What is the purpose of dimensional analysis?

    <p>To check the correctness of a physical equation</p> Signup and view all the answers

    What is the term used to describe the minimum number of units required to express all physical quantities?

    <p>Base units</p> Signup and view all the answers

    What is the relationship between the units of physical quantities?

    <p>They are related to each other through fundamental quantities</p> Signup and view all the answers

    What is the base unit of length in the CGS system?

    <p>Centimetre</p> Signup and view all the answers

    In which year was the SI system of units revised by the General Conference on Weights and Measures?

    <p>2018</p> Signup and view all the answers

    What is the abbreviation for the International System of Units?

    <p>SI</p> Signup and view all the answers

    What is the advantage of using SI units?

    <p>Conversions are quite simple and convenient</p> Signup and view all the answers

    What is the base unit of mass in the FPS system?

    <p>Pound</p> Signup and view all the answers

    How many base units are there in the SI system?

    <p>7</p> Signup and view all the answers

    What is the name of the organization that developed the SI system?

    <p>Bureau International des Poids et measures</p> Signup and view all the answers

    What is the base unit of time in the MKS system?

    <p>Second</p> Signup and view all the answers

    Study Notes

    Units and Measurement

    • Two supplementary units are defined for plane angle dθ and solid angle dΩ.
    • Plane angle dθ is the ratio of the length of arc ds to the radius r, and its unit is radian (symbol: rad).
    • Solid angle dΩ is the ratio of the intercepted area dA of the spherical surface to the square of its radius r, and its unit is steradian (symbol: sr).
    • Both radian and steradian are dimensionless quantities.

    SI Base Quantities and Units

    • There are seven base quantities in the International System of Units (SI).
    • The base quantities and their corresponding units are:
      • Length: metre (m)
      • Mass: kilogram (kg)
      • Time: second (s)

    Introduction to Units and Measurement

    • Measurement of a 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.
    • Although there are many physical quantities, a limited number of units are needed to express them, since they are inter-related.
    • Fundamental or base units are the units for the fundamental or base quantities.
    • Derived units are the units of all other physical quantities, which can be expressed as combinations of the base units.

    The International System of Units

    • The International System of Units (SI) is the system of units currently internationally accepted for measurement.
    • SI was developed by the Bureau International des Poids et Mesures (BIPM) in 1971 and revised in 2018.
    • The SI system uses a decimal system, making conversions within the system simple and convenient.
    • There are seven base units in the SI system, as listed in Table 1.1.

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    Related Documents

    Units And Measurement PDF

    Description

    This quiz covers the units of measurement for plane angle and solid angle, including the definition of radian and its symbol.

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