Question

The smallest division on the main scale of a vernier calipers is $1mm,$ and $10$ vernier divisions coincide with $9$ main scale divisions. While measuring the diameter of a sphere, the zero mark of the vernier scale lies between $2.0$ and $2.1cm$ and the fifth division of the vernier scale coincides with a scale division. The diameter of the sphere is:

• A. $2.05cm$
• B. $3.05cm$
• C. $2.50cm$
• D. None of these

Answer 1

Answer: (A)

The main scale reading of vernier calipers is $MSR=2cm$ . The least count of the vernier calipers is given by,
$LC=\frac{10-9}{100}=0.01cm$
Then the diameter of the sphere is given by,
$D=MSR+n\times \left(LC\right)$ ; where $n$ is the division at which vernier scale coincides with the main scale.
$D=2\times 1+5\times 0.01=2.05cm$ .