Question

The circular divisions of shown screw gauge are 50. It moves 0.5 mm on main scale in one rotation. The diameter of the ball is :

• A. $2.25mm$
• B. $2.20mm$
• C. $1.20mm$
• D. $1.25mm$

Answer 1

Answer: (C)

$1.20mm$

$\text{Zero error}=5\times \frac{0.5}{50}=0.05\text{mm}$

$\text{Actual measurement}$ $=2\times 0.5+25\times \frac{0.5}{50}-0.05\text{mm}$

$=1+0.25-0.05=1.20\text{mm}$