http://www.ck12.org Chapter 13. Heat
FIGURE 13.1
Daniel FahrenheitThe Celsius Scale
The two metric scales are based on the work of Swedish astronomer Anders Celsius, shown in theFigure13.2. His
scale also was defined from zero to 100, but the scale was based on the freezing point and boiling point of water. Zero
degrees Celsius, 0◦C, is the temperature at which water freezes under standard conditions, and one hundred degrees
Celsius, 100◦C, is the temperature at which water boils under standard conditions.
FIGURE 13.2
Anders CelsiusThe Kelvin Scale
The other metric scale was invented later, after it was determined that temperature is based on motion. William
Thomson, titled Lord Kelvin (1824 - 1907),Figure13.3, was an Irish physicist and engineer who devised a
temperature scale that had an absolute zero. Although he did not fully understand the nature of heat, his calculations
predicted there was a minimum temperature where the object had absolutely no heat.
The lowest temperature (0 °K) on the Kelvin scale is equal to “absolute zero” or about -273 °C on the Celsius scale.
The relationship between the two scales is a simple one: If you’re given a temperatureTcmeasured in the Celsius
scale ofx◦Cand wish to find the corresponding temperatureTKin the Kelvin scale, then:TK=TC
(
1 KC
)
- 273 Kor
more simply→TK=TC+273, where the answer is in units of Kelvin.