While measuring the length of a rod with a vernier callipers, figure below shows the position of its scales. What is the length of the rod?

There are 10 divisions on 1 cm on the main scale

∴ Value of 1 main scale division (x) = 1/10 cm = 0.1 cm

Total number of divisions on the vernier scale (n) = 10

L.C. = 0.1/10 = 0.01 cm

Hence, the least count = 0.01 cm.

Main scale reading = 3.3 cm

coinciding division = 6

$\text{Vernier scale reading }=\text{Vernier scale division }\times \text{L.C.}$

$\text{Vernier scale reading }=6\times 0.01\text{cm}$

$\Rightarrow \text{Vernier scale reading }=0.06\text{cm}$

Hence, the Vernier scale reading is 0.06 cm.

$\text{Observed reading }=\text{main scale reading }+\text{vernier scale reading}$

$\text{Observed reading }=3.3\text{cm}+0.06\text{cm}$

$\Rightarrow \text{Observed reading }=3.36\text{cm}$

Hence, the length of the rod is 3.36 cm.