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).