英語翻譯
1 Calibration
To define the temperature scales,a set of calibration points is used; for each,the average thermal energy per molecule is well defined through equilibrium conditions existing between solid,liquid,or gaseous states of various pure materials.Thus,for example,a state of equilibrium exists between the solid and liquid phase of a pure substance when the rate of phase change is the same in either direction:liquid to solid,and solid to liquid.Some of the standard calibration points are
1.Oxygen:liquid/gas equilibrium
2.Water:solid/liquid equilibrium
3.Water:liquid/gas equilibrium
4.Gold:solid/liquid equilibrium
The various temperature scales are defined by the assignment of numerical values of temperatures to the list and additional calibration points.Essentially,the scale differ in two respects:(1) the location of the zero of temperature,and (2) the size of one unit of measure; that is,the average thermal energy per molecule represented by one unit of the scale.
The SI definition of the kelvin unit of temperature is in terms of the triple point of water.This is the state at which an equilibrium exists between the liquid,solid,and gaseous state of water maintained in a closed vessel.This system has a temperature of 273.16 K.