Temperature measuring instruments

Some instruments to measure temperature are thermometer, thermocouple, thermistor etc.


Callendar's compensated constant pressure thermometer

Constant pressure gas thermometer: These thermometers are based on the thermal expansions of gases at constant pressure.

Principle: The increase in volume of a gas at constant pressure is directly proportional to increase in its temperature.

If , ,  are parameters of volume. Then temperature

With air as a thermometric substance can be used to measure temperature upto .

Construction:This constant pressure gas thermometer in which temperature differences between the thermometer bulb and the connecting tubes and manometer used to maintain constant pressure are eliminated by the configuration of the connecting tubes.



Thermometer is an instrument that measures the temperature of a system quantitatively.There are many types of thermometer available for example,liquid in glass thermometer,gas thermometer,resistance thermometer etc.