Question

The following diagram shows a screw gauge when it is closed. What is its zero error? It is given that the least count is 0.01 mm.

• A. -0.98 mm
• B. +0.98 mm
• C. -0.02 mm
• D. +0.02 mm

Answer 1

The correct option is D +0.02 mm

As the zero of the head scale lies below the pitch scale axis, the zero error is positive. Reading of the screw guage is equal to the zero error.

Zero Error = MSR + (n $\times$ L.C)
where:
MSR: Main scale reading
n: Division of head scale
LC: Least count

Zero Error = 0 + (2 $\times$ 0.01 mm)
Zero Error = + 0.02 mm