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Selecting a Thermometer
Reading the Temperature from a Therometer
Measuring the Temperature of a Liquid
Measuring the Temperature of a Solid
Measuring the Temperature of a Gas
Additional Topics
Self Check Exercises
Related Modules
Hot Plate/Magnetic Stirrer

Reading the Temperature from a Therometer


IMAGE. Close-up of a Celcius thermometer.

Step 1: Determine the scale increment:
To find the scale increment, subtract the values of any two adjacent labeled graduations and divide by the number of intervals between them.

check What is the scale increment for the thermometer? Answer

For the thermometer, first subtract 90°C - 80°C = 10°C. Next, count that ten intervals are between the labeled graduations. Therefore, the scale increment is 10°C/10 graduations = 1°C/graduation.

Step 2: Use the graduations to find all certain digits:
Use the labeled graduations and the scale increment to find the certain digits in the measurement.

checkWhat are all of the certain digits for the thermometer? Answer

The temperature is greater than 80°C, since the last labeled graduation below the meniscus is 80°C. Next, use the scale increment. There are seven graduation marks below the meniscus, and each graduation represents 1°C, so the certain digits of the reading are 87°C.

Step 3: Estimate the uncertain digit and obtain a reading:
Estimate the distance that the meniscus lies between the two graduations as a decimal fraction and multiply by the scale increment.

checkWhat is the temperature you should record? Answer

The bottom of the meniscus is about seven tenths of the way between the two graduation marks. Thus, the uncertain digit is calculated as (0.7 increment) * (1°C/increment) = 0.7°C. And, the temperature to be recorded is 87.7°C.