Thread rolling is restricted to

If the elongation factor during rolling of an ingot is $$1.22.$$ The minimum number of passes needed to produce a section $$250 \times 250\,\,mm$$ from an ingot of $$750 \times 750\,\,mm$$ are

To stress relive a cold worked steel part, it is heated to a temp close to ..... A....... and grains obtained after cooling are........ B.........
A. Lower critical temp/ upper critical temp
B. Fine / coarser

In an interference microscope, a groove produces a band distortion of $$4$$ band spacing. If the wave length of the monochromatic light source is $$0.5microns,$$ the groove depth is ......................$$mm$$