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?
Correct option is C) Most precise device is the one with the minimum least count 1. Vernier Calliper 20 divisions on the sliding scale L.C= 20 1 mm=0.05mm 2. Screw Gauge pitch 1 mm and 100 divisions on the circular scale L.C= 100 1mm =0.01mm 3.optical instrument within a wavelength of light Wavelenght of light ≈ 589nm Hence Optical instrument is the most precise
