First slide
Measurement
Question

The pitch of a screw gauge is 1 mm and there are 100 divisions on circular scale. When faces A and B are just touching each other without putting anything between the studs 32 nd division of the circular scale coincides with the reference line. When a glass plate is placed between the studs, the linear scale reads 4 divisions and the circular scale reads 16 divisions. Find the thickness of the glass plate. Zero of linear scale is not hidden from circular scale when A and B touches each other.

Moderate
Solution

Least count (L C) = Pitch  Number of divisions on circular scale =1100mm

= 0.01 mm

As zero is not hidden from circular scale when A and B touches each other. Hence, the screw gauge has positive error.

e=+n(LC)=32×0.01=0.32 mm

Linear scale reading =4×(1 mm)=4 mm

Circular scale reading =16×(0.01 mm)=0.16 mm

Measured reading =(4+0.16)mm=4.16 mm

Absolute reading = Measured reading -e

=(4.16-0.32)mm=3.84 mm

Therefore, thickness of the glass plate is 3.84 mm.

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