Question

In a vernier caliper, 20th division on the vernier scale coincides with the seventeenth division on the main scale. If 1 cm on the main scale. If 1 cm on the main scale is divided into 20 equal parts, then what is the least count of the calipers.

• A. 0.085 mm
• B. 0.0075 mm
• C. 0.0085 mm
• D. 0.075 mm

Answer 1

The correct option is D 0.075 mm

Length of one main scale division $1M.S.D.=\frac{1cm}{20}=0.05cm=0.5mm$

Since, 20th division of vernier scale coincides with 17th division of main scale.

Least count of vernier callipers, $L.C.=1M.S.D.-\frac{17}{20}\times M.S.D.$

$⟹L.C.=0.5mm-\frac{17}{20}\times 0.5mm=0.075mm$

Correct answer is option D.