Question

Under which group, does third order irregularities fall?

(a) Primary group

(b) Secondary group

(c) First group

(d) Second group

The question was posed to me at a job interview.

Query is from Meaning of Surface Texture topic in division Measurement of Surface Finish of Engineering Metrology

Answer 1

Right choice is (d) Second group

To explain: Irregularities of small wavelength falls under second group and caused by the direct action of the cutting element or by some disturbance such as friction. It includes irregularities of third and fourth order.