Question

The given diagram represents a screw gauge. The circular scale is
divided into 100 divisions and the linear scale is divided into millimetres. If the screw advances by 1 mm when the circular scale makes 2 complete revolutions, find the least count of the instrument and the reading of the instrument in the figure.

• A. $3.16\text{mm}$
• B. $3.16\text{cm}$
• C. $03.16\text{cm}$
• D. $0.316\text{mm}$

Answer 1

The correct option is A $3.16\text{mm}$

LC $=\frac{\text{Pitch}}{\text{Number of CSD}}$
$=\frac{0.5}{100}=0.005\text{mm}$
From the figure,
MSR $=3\text{mm}$
CSD$=32$
Reading = MSR + CSD × LC $=3+32\times 0.005$
$=3.16\text{mm}$
$=0.316\text{cm}$