Concept preview

What you will be able to do

1. 01Read a calibrated scale to the correct number of digits
2. 02Report a measurement with a suitable uncertainty in the right place value
3. 03Distinguish accuracy from precision

A measuring scale is marked off ('calibrated') at regular intervals, with larger numbered divisions and smaller unnumbered subdivisions between them. To read it, first find the difference between numbered divisions, then count the unnumbered subdivisions to find the value of each small interval. On a centimetre scale where the numbered divisions differ by $0.1\ \text{cm}$ and there are ten subdivisions, each subdivision is worth $0.01\ \text{cm}$. Getting the value of the smallest marked interval is the first step in every reading.