Question

A vernier caliper has 20 divisions on the vernier scale, which coincide with 19 on the main scale. If one main scale division is 2mm, then the least count of the instrument is what?

Answer 1

VSD - Vernier scale divisions.   MSD - Main scale divisions.  

Given that 20 VSD = 19 MSD
Then 1 VSD = (19)/(20) MSD= 0.95 MSD.

Least count of Vernier calipers, LC  = 1 MSD -1 VSD
            = 1 MSD - 0.95 MSD = 0.05 MSD.
As 1 MSD = 2mm,  
Least count, LC = 0.05 x 2 mm = 0.1 mm.

Answer 2

Answer:

least count of instrument-0.1mm

Explanation:

VSD- Vernier scale division

MSD- main scale division

20 divisions on the vernier scale, which coincide with 19 on the main scale.

20VSD=19MSD

then for 1VSD=19/20MSD

Least count of vernier scale =1MSD-1VSD

1MSD-19/20MSD

20-19/20MSD

1/20MSD

1MSD=2mm

1/20MSD=1/20*2mm

= 0.1mm

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