Which of the following is the most precise device for measuring length 

  • A

    a vernier callipers with $20$ divisions on the sliding scale

  • B

    a screw gauge of pitch $1\,\, mm$ and $100$ divisions on the circular scale

  • C

    an optical instrument that can measure length to within a wavelength of light

  • D

    Precison can not be changed by changing the instrument.

Similar Questions

In a Vernier Calipers. $10$ divisions of Vernier scale is equal to the $9$ divisions of main scale. When both jaws of Vernier calipers touch each other, the zero of the Vernier scale is shifted to the left of $zero$ of the main scale and $4^{\text {th }}$ Vernier scale division exactly coincides with the main scale reading. One main scale division is equal to $1\,mm$. While measuring diameter of a spherical body, the body is held between two jaws. It is now observed that zero of the Vernier scale lies between $30$ and $31$ divisions of main scale reading and $6^{\text {th }}$ Vernier scale division exactly. coincides with the main scale reading. The diameter of the spherical body will be $.......cm$

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In an experiment with Vernier callipers of least count $0.1\,mm$, when two jaws are joined together the zero of Vernier scale lies right to the zero of the main scale and $6^{\text {th }}$ division of Vernier scale coincides with the main scale division. While measuring the diameter of a spherical bob, the zero of vernier scale lies in between $3.2\,cm$ and $3.3\,cm$ marks, and $4^{\text {th }}$ division of vernier scale coincides with the main scale division. The diameter of bob is measured as $.......\,cm$

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A specially designed Vernier calliper has the main scale least count of $1 \,mm$. On the Vernier scale, there are $10$ equal divisions and they match with $11$ main scale divisions. Then, the least count of the Vernier calliper is ........... $mm$

  • [KVPY 2019]