Question

Upto which limits irregularities can be detected with touch inspection of a surface?

(a) 0.0001 mm

(b) 0.001 mm

(c) 0.01 mm

(d) 0.1 mm

The question was asked in an interview for job.

This key question is from Methods of Measuring Surface Finish topic in division Measurement of Surface Finish of Engineering Metrology

Answer 1

Correct answer is (c) 0.01 mm

The best explanation: Touch inspection method can tell which surface is rougher. In this method, the finger-tip is moved along the surface at a speed of about 25/sec and the irregularities of about 0.01 mm can be easily detected.