The Physics of Temperature-Taking

When we measure the temperature of a body, we are depending on the heat of the body to be transferred to (or from) our measuring device. Once the heat has been taken to (or from) our measuring device, any physical changes in that device are interpreted as a temperature change. The process where we analyze the effects caused by a property to determine the amount of that property is known as inferred measurement. For temperature we have a variety of physical properties from which to infer the amount of energy (heat) that a given object has. 

Measurement of temperature (or any energy property) has one major difference from measurement of physical materials It is not cumulative. To measure the length of a room, you can lay several meter sticks end to end. The sum of the number of meter sticks will be the length of the room. Temperature, however, is not cumulative. If you have a liquid that is hotter than the range of temperatures measurable on one thermometer, you cannot use a second thermometer to obtain the remaining temperature. 

Because the temperature ranges and conditions of a system can vary, a variety of materials have been incorporated into different types of thermometers. The following is a list of common thermometer types and the property measured in each to obtain a heat measurement. 

Liquid-in-glass thermometer. Volume of liquid increases as heat 

Gas or vapor at constant volume. Pressure of gas increases as heat 

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