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?

Question

Philoid · Accepted Answer

In this question, three measuring/ calibrating instruments are given. Among these devices, we have to find the most precise device.

To find the most precise device we have to calculate the Least Count of these devices.

(a). Least count of Vernier calliper =

= = 0.05 mm

= 0.05 cm

(b). Least count (L.C) of screw gauge =

Pitch = 1 mm

No. of division on circular scale = 100

L.C = 1 × 10^-3 ×

= 0.01 cm

(c). Least count of optical instrument that can measure length to within a wavelength of light is about 0.00001 cm

Here optical instrument has least count among given instruments. So Optical instrument is the most precise device for measuring length.

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?