Question

In a vernier callipers, 20 divisions on the vernier scale coincides with 17 divisions on the main scale. If one cm on the main scale is divided into 20 equal parts, then find the least count of the callipers.

Answer 1

20 VSD $=$ 17 MSD
1 cm $=$ 20 equal divisions (MSD)
$\therefore 1MSD=\frac{1}{20}cm=0.5mm$
$L.C=1MSD-1VSD$
$0.05-\frac{17}{20}\times 0.05=0.0075cm$