A screw gauge with a pitch of 0.5mm and a circular scale with 50 division is used to measure the thickness of the thin sheet of aluminium. The two jaws of a screw gauge are brought in contact the 45th division coincides with the main scale and that the zero of the main scale is barely visible what is the thickness of the sheet if the main scale reading is 0.5.mm and the 25th division coincides with the main scale line?
