The Total solution for NCERT class 6-12
Which of the following is the most precise device for measuringlength:
(a) a vernier callipers with 20 divisions on the sliding scale
(b) a screw gauge of pitch 1 mm and 100 divisions on the circularscale
(c) an optical instrument that can measure length to within awavelength of light ?
A device with minimum count is the most suitable to measurelength.
(a) Least count of vernier callipers
= 1 standard division (SD) – 1 vernier division (VD)
(b) Least count of screw gauge =
(c) Least count of an optical device = Wavelength of light ∼ 10–5 cm
= 0.00001 cm
Hence, it can be inferred that an optical instrument is the mostsuitable device to measure length.