Lakeshore 332 User Manual page 173

B1.0 DEFINITION
Temperature is a fundamental unit of measurement which describes the kinetic and potential energies
of the atoms and molecules of bodies. When the energies and velocities of the molecules in a body are
increased, the temperature is increased whether the body is a solid, liquid, or gas. Thermometers are
used to measure temperature. The temperature scale is based on the temperature at which ice, liquid
water, and water vapor are all in equilibrium. This temperature is called the triple point of water and is
assigned the value 0 °C, 32 °F, and 273.15 K. These three temperature scales are defined as follows:
Celsius. Abbreviation: °C. A temperature scale that registers the freezing point of water as 0 °C and the
boiling point as 100 °C under normal atmospheric pressure. Formerly known as "Centigrade."
Originally devised by Anders Celsius (1701 – 1744), a Swedish astronomer.
Fahrenheit. Abbreviation: °F. A temperature scale that registers the freezing point of water as 32 °F
and the boiling point as 212 °F under normal atmospheric pressure. Originally devised by Gabriel
Fahrenheit (1686 – 1736), a German physicist residing in Holland; developed use of mercury in
thermometry.
Kelvin. Abbreviation: K. An absolute scale of temperature, the zero point of which is approximately
–273.15°C. Scale units are equal in magnitude to Celsius degrees. Originally devised by Lord
Kelvin, William Thompson, (1824 – 1907), a British physicist, mathematician, and inventor.
B2.0 COMPARISON
The three temperature scales are graphically compared in Figure B-1.
Freezing point of water
B3.0 CONVERSIONS
To convert Fahrenheit to Celsius: subtract 32 from °F then divide by 1.8, or:
°C = (°F – 32) ÷ 1.8
To convert Celsius to Fahrenheit: multiply °C by 1.8 then add 32, or:
°F = (1.8 × °C) + 32
To convert Fahrenheit to kelvin, first convert °F to °C, then add 273.15.
To convert Celsius to kelvin, add 273.15.
Temperature Scales
Lake Shore Model 332 Temperature Controller User's Manual
APPENDIX B
TEMPERATURE SCALES
Boiling point of water
Absolute zero
kelvin
Figure B-1. Temperature Scale Comparison
373.15 K 100 °C
273.15 K 0 °C
0 K ­273.15 °C
Celsius
212 °F
32 °F
­459.67 °F
Fahrenheit
B-1