A screw gauge with a pitch of 0.5 mm and a circular scale with 50 divisions is used to measure the thickness of a thin sheet of Aluminium. Before starting the measurement, it is found that when the two laws of the screw gauge are brought in contact, the 45^(th) division coincides with the main scale is barely visible. What is the thickness of the sheet is the main scale reading is 0.5 mm and the 25^(th) division coincides with the main scale line ?

A screw gauge with a pitch of 0.5 mm and a circular scale with 50 divi

1.	A screw gauge with a pitch of 0.5 mm and a circular scale with 50 divisions is used to measure the thickness of a thin sheet of Aluminium. Before starting the measurement, it is found that when the two laws of the screw gauge are brought in contact, the 45^(th) division coincides with the main scale is barely visible. What is the thickness of the sheet is the main scale reading is 0.5 mm and the 25^(th) division coincides with the main scale line ?
Answer» `0.50 MM` `0.75 mm` `0.80 mm` `0.70 mm` Solution :Leas count `=(0.5)/(50)=(1)/(100)=0.01 mm` ZERO ERROR `=-5xx0.01=0.05 mm` Reading `=0.5+(25)/(100)=0.75 mm` `:.` Thickness `=0.75-(-0.05)=0.80 mm`