Question

The smallest division on main scale of a vernier callipers is $1mm$ and $10$ vernier divisions coincide with $9$ scale divisions. While measuring the length of a line, the zero mark of the vernier scale lies between $10.2cm$ and $10.3cm$ and the third division of vernier scale coincide with a main scale division. Determine the least count of the callipers.

• A. $0.01cm$
• B. $0.001cm$
• C. $0.02cm$
• D. $0.002cm$

Answer 1

The correct option is A $0.01cm$

Given, $1MSD=1mm$

Least count of calipers, $Lc=1MSD-1VSD$

Here, $10VSD=9MSD$ or $1VSD=\left(9/10\right)MSD$

So, $Lc=1MSD-\left(9/10\right)MSD=\left(1/10\right)MSD=\left(1/10\right)1mm=0.1mm=0.01cm$