Question

question
when reading a measurement from an analog instrument like a ruler or a mercury thermometer, how should you determine the number of significant figures to record?
select the correct answer below:
the least significant figure should be the place value of the smallest markings on the instrument.
the least significant figure should be estimated by reading between the smallest markings on the instrument.
the least significant figure should be one place - value greater than the smallest markings on the instrument.
use as many significant figures as the number of repeated measurements.

Explanation:

When using analog instruments (e.g., rulers, mercury thermometers), the smallest marking gives the precision of the instrument. But to get a more accurate measurement, we estimate one digit beyond the smallest marking. For example, if a ruler has markings every \(1\) mm (\(0.1\) cm), we can estimate to the \(0.1\) mm (\(0.01\) cm) place. This estimated digit is the least - significant figure. Option A is incorrect because just taking the place value of the smallest marking doesn't account for the estimation. Option C is wrong as we don't go one place - value greater (we go one digit beyond the smallest marking's precision). Option D is incorrect because the number of significant figures is related to the instrument's precision and estimation, not the number of repeated measurements.

Answer:

B. The least significant figure should be estimated by reading between the smallest markings on the instrument.