PX154 - B1 - heat and temperature
[YF17]
temperature
- a physical property related to the kinetic energy of the atoms, molecules and/or electrons of the system under study
- this energy is the "internal energy" of the system, given the symbol
- this energy is the "internal energy" of the system, given the symbol
temperature scales
- we need some observable property that changes predictably with temperature
- eg: mercury/alcohol based thermometers, thermocouples, infrared measurements, behaviour of ideal gases (using
)
- eg: mercury/alcohol based thermometers, thermocouples, infrared measurements, behaviour of ideal gases (using
- ideally, we want a linear dependence of the property on temperature:
- where,
value at some temperature, some constant - let's use two fixed points:
- eg:
- ice point (freezing/melting of pure water)
- steam point (boiling point of pure water - mix of water/gas)
- set:
- ice point
- set steam point
- ice point
- we can use these two fixed points to calibrate our thermometer

- eg:
- where,