Question

In a screw gauge, when a movable stud is in contact with a fixed stud, the 44th division of the head scale is found to be on the index line. If the pitch scale is calibrated in mm with a pitch of 1 mm and the number of divisions on the head scale is 50, then the zero correction is _________ mm.

• A. $+1.2$
• B. $–1.2$
• C. $+0.12$
• D. $–0.12$

Answer 1

The correct option is C

$+0.12$

Step 1:Given the data and formula used

Given:

Number of head scale divisions$=50$

Pitch$=1\mathrm{mm}$

Formula used

Least count $\mathrm{L}.\mathrm{C}=\frac{\mathrm{pitch}}{\mathrm{Number}\mathrm{of}\mathrm{head}\mathrm{scale}\mathrm{divisions}}$

Step 2: Calculation for error and correction

On putting given value in formula

$$\begin{gathered} \mathrm{L}.\mathrm{C}=\frac{1\mathrm{mm}}{50}=0.02\mathrm{mm} \\ \mathrm{Error}=-6\times \mathrm{L}.\mathrm{C}=-6\times 0.02=-0.12 \end{gathered}$$

We know correction$=-$ error

Hence correction$=+0.12$

Hence, the correct option is (c).