A Levels Physics

A digital caliper is used to measure the 28.50 mm width of a plastic ruler. The digital caliper reads
to the nearest 0.01 mm.
What is the correct way to record this reading?
A 0.02850 + 0.01 m
B
0.0285 + 0.001m
C (2.850 + 0.001) × 10-2m
D (2.850 ± 0.001) × 10-°m


Choice C is correct because:

Uncertainties of readings should always be given to 1sf while the reading should be given to the same number of decimal places as the uncertainty.

The uncertainty in the digital caliper is 0.01mm. 0.01mm = 0.01 × 10^{-3}m = 0.001 × 10^{-2}m.

The reading should be measured to the same number of decimal places. 28.50mm = 28.50 × 10^{-3}m = 2.850 × 10^{-2}m.

Choices A, B, and D are incorrect because they state the wrong readings of the digital caliper.

Physical Quantities and Units | 2014 - M/J - 9702/13 | Q6