The main scale, of a given screw gauge, has been graduated in ‘half millimeters’.
The moving jaw of this screw gauge advances through 2.5 mm, on the main scale, when the screw is given five complete rotations. There are 100 divisions on its circular scale.
The zero of the circular scale, coincides with the zero of the main scale when the moving face end just coincides with its fixed face end.
When a thin sheet is just held between the jaws of the screw guage, the main scale reads 0.55 cm while the 43rd division, of the circular scale, lies along the line of graduations of the main scale. The least count of this screw gauge, and the thickness of the sheet, are equal, respectively, to
(1) 0.0005 mm and 0.5715 cm
(2) 0.0005 cm and 0.55215 cm
(3) 0.0005 mm and 0.55215 cm
(4) 0.0005 cm and 0.5715 cm