Question

The diagram shows part of the vernier scale on a pair of calipers(10 divisions on vernier coincide with 9 divisions on main scale).
Which reading is correct?

• A. $2.74cm$
• B. $3.10cm$
• C. $3.26cm$
• D. $3.64cm$

Answer 1

The correct option is A $2.74cm$

$\begin{array}{c}\text{Given that:}\\ \begin{array}{c}\text{10VSD}=9MSD\\ \text{1VSD}=0.9mSD\end{array}\\ \text{Also,}\\ \text{From the given diagram}\end{array}$

$\begin{array}{cc}\mathrm{1\; MSD}& =0.1cm\\ \text{1 VSD}& =0.9\times 0.1cm\\ & =0.09cm\\ & =1mSD-1VSD\\ & =0.1-0.09\\ & =0.01cm\end{array}$

$\text{Reading}=MSR+VSR$

$\begin{array}{cc}& =2.7cm+(4\times 0.01)\\ & =2.74cm\end{array}$