Question

If the length of a vernier scale having $20$ divisions corresponding to $19$ main scale divisions and given that $1MSD=1mm$, then the least count of the vernier callipers is

• A. $0.1mm$
• B. $50\mu m$
• C. $0.05mm$
• D. $1\times {10}^{-4}cm$

Answer 1

The correct option is C $0.05mm$

Least count, $L.C=1MSD-1VSD$

Where $MSD=$ main scale division and $VSD=$ vernier scale division

Here, $20VSD=19MSD$ or $1VSD=\left(19/20\right)MSD$

Thus, $L.C=1MSD-\left(19/20\right)MSD=\left(1/20\right)MSD=\left(1/20\right)\left(1mm\right)=0.05mm$ ( as $1MSD=1mm$)