Question

which is more precise device-

1a vernier callipers with 20 divisions on the sliding scale

2 a screw gauge of pitch 1 mm and 100divisions on the circular scale

3 an optical instrument that can measure length to within a wavelength of light?

Answer 1

1>The vernier capillers are more accurate when 10 division conside with the main scale.
2> the screw gauge gives more accurate value when its 100division conside with circular scale hence this is upto mark of accuracy hence this device can give more accurate value as compared to other
3> the optical instruments which measures length can varies depending upon the
a> temperature
b> abbreatation etc.