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 ?

Options

A. Vernier calipers
B. Screw gauge
C. Optical instrument
D. All the above

Answer

C