A micrometre screw gauge has a negative zero error of 0.0018cm. The main scale reading is 3.6cm for an object. The baseline coincides with the 45th division of the circular scale. Calculate the true length of the object in mm.
36.063
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Solution
The correct option is A 36.063 Given: Negative zero error, E=−0.0018cm Main scale reading, MSR =3.6cm The circular scale division coinciding with the baseline, p=45 Least count of a micrometre screw gauge, L.C. =1μm=0.001mm=0.0001cm Observed length = MSR + (p × L.C.) = 3.6+(45×0.0001cm)=3.6045cm True length = Observed length - Negative zero error = 3.6045−(−0.0018) = 3.6063cm=36.063mm.