In a vernier callipers, `N` divisions of the main scale coincide with `N + m` divisions of the vernier scale. what is the value of `m` for which the instrument has minimum least count.

Options

A. 1
B. N
C. infinity
D. `N//2`

Answer

A

Explanation

`L.C = 1 MSD - 1 VSD` but `(N) MSD = (N + M)(VSD)`
`rArrL.C=1MSD-((N)/(N+m))MSD`
`= ((m)/(N+m))=((1)/((N)/(m)+1))MSD`
For minimum least count, m should be minimum so `m =1`