Question

Which of the following option is not true for flatness testing?

(a) Geometrical plane can be represented by a family of straight lines

(b) Flatness can be tested by grid and half grid method

(c) Three and four edge type straight edge cannot be used for this purpose

(d) Geometrical plane can be represented by a surface plane

I had been asked this question by my college professor while I was bunking the class.

My question comes from Flatness Testing in division Straightness, Flatness, Squareness, Parallelism, Circularity and Rotation of Engineering Metrology

Answer 1

Correct option is (c) Three and four edge type straight edge cannot be used for this purpose

Explanation: Three and four edges straight edges can be used to test flatness by applying prussian blue on the working edges and then drawing the straight edge across the surface.