Question

The diameter of a wire is measured with a screw gauge having $50$ divisions on circular scale and by one complete rotation of circular scale, main scale moves $0.5\text{mm}$. If reading of screw gauge is $0.250\text{cm}$. The minimum percentage error in the reading will be

• A. $4$
• B. $0.8$
• C. $0.4$
• D. $5$

Answer 1

The correct option is C $0.4$

Least count of screw gauge = $\frac{0.5}{50}=0.01\text{mm}$

Percentage error in diameter = $\frac{0.01}{2.50}\times 100=0.4\%$

$\therefore \left(a\right)$