Question

The least count of a vernier caliper is 0.01 cm and if the length of the rod measured by it is 60.5 mm and observed vernier coincidence is 5, then the division of the main scale nearer to which zero division of vernier lies is _________.

• A. $45$
• B. $65$
• C. $50$
• D. $60$

Answer 1

The correct option is D

$60$

Step 1: Given value and formula used

$\mathrm{MSR}$ is the main scale reading, $\mathrm{VCD}$ is the Vernier caliper division, $\mathrm{LC}$ is the least count

Least count $=0.01cm,V.C.D.=5$
Measured length$\left(l\right)=60.5mm=6.05cm$
Let n be the nth division on the main scale
$N=?$
$$\begin{gathered} \mathrm{Measured}\mathrm{length}=\mathrm{M}.\mathrm{S}.\mathrm{R}.+(\mathrm{V}.\mathrm{C}.\mathrm{D}.\times \mathrm{L}.\mathrm{C}.) \\ \mathrm{M}.\mathrm{S}.\mathrm{R}.=\mathrm{measured}\mathrm{length}–(\mathrm{V}.\mathrm{C}.\mathrm{D}.\times \mathrm{L}.\mathrm{C}.) \end{gathered}$$

Step 2: Calculation of main scale reading

On putting given value
$\mathrm{M}.\mathrm{S}.\mathrm{R}=6.05–(5\times 0.01)\mathrm{nth}\mathrm{division}=60th$ division on the main scale.
Hence, the correct option is (d).