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?

  • 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

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