Question

A vernier caliper has $1\text{mm}$ marks on the main scale. It has $20$ equal divisions on the vernier scale which match with $16$ main scale divisions. For this vernier caliper, the least count is

• A. $0.02\text{mm}$
• B. $0.05\text{mm}$
• C. $0.1\text{mm}$
• D. $0.2\text{mm}$

Answer 1

The correct option is D $0.2\text{mm}$

$MSD$ = Main scale divisions
$VSD$ = Vernier scale divisions
From question,
$1MSD=1\text{mm}$ and, $20VSD=16MSD$
$\Rightarrow 1VSD=\frac{16}{20}\times MSD=\frac{16}{20}\times 1=0.8\text{mm}$
Vernier constant$\left(VC\right)$ or Least count$\left(LC\right)$,
$=1MSD-1VSD=1.0-0.8=0.2\text{mm}$
Hence, option $\left(d\right)$ is the correct answer.