Question

3 divisions of a simple scale coincide with 5 divisions of another scale. If one division of the simple scale measures 1 mm, then minimum distance that can be measured with the combination of these two scales is

• A. 0.6 mm
• B. 0.5 mm
• C. 0.4 mm
• D. 0.2 mm

Answer 1

The correct option is D 0.2 mm

The question is describing a vernier caliper


Least count of a vernier caliper

$L.C=2\times V.S.D-1\times M.S.D$
where V.S.D is the Vernier Scale Divison and M.S.D is the Main Scale Division.

Given 5 V.S.D = 3 M.S.D and
1 V.S.D = 0.6 mm

$\therefore L.C=2\times V.S.D-1\times M.S.D=2\times 0.6-\left(\frac{5}{3}\right)\times 0.6=0.2mm$