Types of thermometers Flashcards
Liquid in glass
Liquid exapands as temperature rises
Liquid in gas advantages
Easy to use, portable, high precision
Liquid in gas disadvantages
-Fragile
-Resitricted range
-Must be read directly
-cannot measure the temperture of small objects
Plantinum resistance
Resistance increses linearly as temperature rises
Platinum resistance advantages
-Very accurate
-Wide range of temperatures
-Can be used remotely
Platinum Resistance disadvantages
-Slow response
-cannot measure small objects
Thermistor
Resistance decreases or increases as temperature rises
Thermistor advantages
Low cost, small size
Thermistor Disadvantages
Non-linear and relatively small range of operating temperature
Thermocouple
E.m.f produced across thermocouple which depends on the difference in temperature between the two thermocouple junctions
Thermocouple advantages
-Fast response
-wide range
-remote readings possible with long leads
-can measure themperature at a specific point
Thermocouple disadvantages
-metals can corrode
-one junction needs to be maintained at a constant temp
-e.m.f produced is small so sensitive intrument needed to measure e.m.f
Constant volume gas thermometer
Pressure of gas increases with increasing temp
Constant volume gas termometer Advantages
-Wide range
-Very accurate
-Used as a standard thermometer to calibrate other types of termometers
