Figure 2.12

The Kelvin, Celsius, and Fahrenheit scales. The thermometer at the right reads “0 degrees Celsius” or “32 degrees Fahrenheit.” That same temperature is “273 kelvins,” as shown on the thermometer at the left. A fluid (mercury or red-colored alcohol) in the glass tube of a thermometer expands and contracts as its temperature changes, resulting in a lowering or raising of the fluid’s level.