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 ......................$$mm$$

The diameter of the best wire to measure the effective diameter of a metric screw threads of $$0.5$$ $$mm$$ pitch is ......... $$mm$$

Powder metallurgical components have

The skid in a stylus type roughness measuring instrument is used to provide ............ A .............. and define ................... B .............. geometrical profile of the surface.

$$A.$$ support / datum
$$B.$$ micro / macro