Question

How the straightness of any surface can be determined with the help of spirit level?

(a) By finding relative angular positions at extreme sections of the surface

(b) By finding relative linear distance at middle of the surface

(c) By finding relative angular positions at adjacent section

(d) By finding relative angular positions at any point

I have been asked this question during a job interview.

I would like to ask this question from Test for Straightness by using Spirit Level and Autocollimator in portion Straightness, Flatness, Squareness, Parallelism, Circularity and Rotation of Engineering Metrology

Answer 1

Right answer is (c) By finding relative angular positions at adjacent section

For explanation I would say: In case of the spirit level, the angular variations are measured by the sensitive level on it which gives the difference of height between two points by knowing the spirit level’s least count.