Which of the following option is true for scales and gratings?
(a) Ruling in scales are closely spaced
(b) Ruling in gratings is far apart
(c) Vernier device is required with scales
(d) Ruling in scale forms a periodic pattern
I had been asked this question during an internship interview.
The above asked question is from Scales and Gratings topic in portion Measurement by Light-Wave Interference of Engineering Metrology