University of Illinois Extension

Using a Thermometer

A more accurate way to measure temperature is by using a thermometer. A thermometer is the instrument used to tell the air temperature. A thermometer is usually made up of a small, hollow glass tube. At the bottom of the tube is a bulb, which holds a liquid such as alcohol or mercury.

When there is an increase in heat, the liquid inside the bulb expands, pushing up into the tube. A decrease in heat lets the liquid contract, moving down the tube. A measuring scale is attached to the tube, to give an accurate measurement of heat energy.


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