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Uncertainty 

A precise measurement is the one which has less precision or absolute uncertainty and an accurate measurement is the one which has less fractional or percentage uncertainty or error.
In measurements made in physics, the terms precision and accuracy are frequently used. They should be distinguished clearly. The precision of a measurement is determined by the instrument or device being used and the accuracy of a measurement depends on the fractional or percentage uncertainty in that measurement. Fractional uncertainty = (0.1 cm / 25.5 cm) Percentage uncertainty = (0.1 cm / 25.5 cm) X (100 / 100) = 0.4 / 100 = 0.4 % Another measurement taken by vernier calipers with least count as 0.01 cm is recorded as 0.45 cm. it has Precision or absolute uncertainty (least count) = ± 0.01 cm Fractional uncertainty = (0.01 cm / 0.45 cm) = 0.02 Percentage uncertainty = (0.01 cm / 0.45 cm) X (100 / 100) = (2.0 / 100) = 2.0 %
Thus the reading 25.5 cm taken by metre rule is although less precise by is more accurate having less percentage uncertainty or error. A precise measurement is the one which has less precision or absolute uncertainty and an accurate measurement is the one which has less fractional or percentage uncertainty or error. 



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