Ncert Exercises & Solutions

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

1.	a vernier callipers with \(20\) divisions on the sliding scale.
2.	a screw gauge of pitch \(1\) mm and \(100\) divisions on the circular scale.
3.	an optical instrument that can measure the length within a wavelength of light.
4.	both (1) and (2).

Hint: The instrument with the minimum least count will be the most precise instrument to measure the length.

Step 1:

Least count of Vernier Calliper = 0.05 mm

Least count of Screw Gauge = 0.01 mm

Least count of Optical instrument = 0.1

μm

Step 2:

Hence, among the given options, the optical instrument will be the most precise instrument.