Chapter 2
TEMPERATURE
Zeroth law of Thermodyamics
• The zeroth law of thermodynamics states that if two thermodynamic systems are each in thermal equilibrium with a third one, then they are in thermal equilibrium with each other.
• Zeroth law of thermodynamics is the basis of temperature measurement
Thermometer | Thermometric property |
Constant vol. gas thermometer | Pressure (P) |
Consant pressure gas thermometer | Volume (V) |
Resistance thermometer (Thermistor) | Resistance (R) |
Thermo couple | EMF (e) |
Mercury in glass thermometer | Length (L) |
Thermometer | Temp. range |
Platinum resistance Thermometers | –200ºC – 1200ºC |
Thermoelectric thermometers | –200ºC – 1600ºC |
Radiation pyrometers | above 400ºC |
Segar cone | 600ºC – 2000ºC |
Optical pyrometers | above 650ºC |
Gas Thermomenters | –200ºC – 1200ºC |
Temperature
The temperature is a measure(degree) of hotness or coldness.(freezing cold, warm hot)
Temperature scales
T(K) = T(C) + 273.16
T(K) = T(C) = 459.67
T(R) = 1.8T(K)
T(0F) = 1.8T(0C) + 32
ΔT(0F) = 1.8ΔT(K) = ΔT(R)