a micrometer screw gauge has a positive error of 7 divisions such that its main scale is marked in 1/2mm and the cicular scale has 100 divisions.the spindle of a screw gauge advances by 1 division for 1 complete rotation.if the screw gauge reading is 9 divisions on main scale and 67 divisions on circular scale fr the of a thin wire.calculate

1.pitch

2.LC

3.observed diameter

4.corrected diameter

Main scale (or linear scale) is marked 1/2 mm.

Pitch is the distance travelled by the spindle per revolution. The screw gauge advances by a distance of 1/2 mm (0.5 mm) per complete rotation. Thus this is the pitch of the screw gauge

1) Pitch= 0.5 mm

2) Least Count:

3) Observed Diameter:

Reading: =MSR+(nX LC)  mm

 =9+(67X 0.005) mm

 =9.335mm

4) Corrected Reading of the diameter:

Positive Zero Error of 7 divisions. 

Thus, the corrected reading of main scale divisions would be=9-7=2 divisions

Therefore, Reading=2+(67X0.005)= 2.335 mm