In a vernier callipers N divisions of vernier scale coincide with `N-1` divisions of main scale (in which length of one divisions is 1mm). The least count of the instrument should be

Options

A. N
B. `N-1`
C. `(1)/(10 N)`
D. `(1)/(N-1)`

Answer

C

Explanation

Least count = 1 MSD - 1 VSD
`(N -1)MSD=N(VSD) rArr VSD = (1-(1)/(N))MSD`
Least count `= 1MSD - (1-(1)/(N))MSD`
`= ((1)/(N))(1mm)=(1)/(10 N)cm`