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Can you explain the working of constant volume gas thermometer and constant pressure gas thermometer

Asked by sureshkalanjoor 14th January 2017, 7:51 PM
Answered by Expert

Constant Volume Gas Thermometer:

  • A constant volume gas thermometer ususally consists of a bulb filled with a fixed amount of a dilute gas which is attached to a mercury manometer. 
  • The manometer is used to measure variation in pressure.
  • This thermometer works on the principle of Law of Gay-Lussac.
  • The law states that when the temperature of an ideal gas increases, there is a corresponding increase in pressure. 
  • Also, when the temperature decreases, the pressure too decreases correspondingly. 
  • This is how constant volume gas thermometers traces the increase in temperature with the change in pressure while the volume remains constant. 
  • These types of thermometers are used in calibration of various other thermometers.
 Constant Pressure Gas Thermometer:
  • The constant pressure gas thermometer is based on the relationship between the variation in voluime with the corresponding variation in the temperature while the pressure of the process remains constant. 
  • This consists of  a long, thin glass tube with a known constant mass of air and mercury sealed inside by a rubber stopper. 
  • Such processes are called as the Isobaric process.
  • The tube, air, and mercury are then surrounded by a larger, opentube through which liquid or gas can freely pass. 
  • On changing the temperature of the inner tube, the air either expands or contracts, moving the mercury along the tube.
  • Measuring the amount of movement of the mercury gives us a relationship to how much it has expanded at certain temperatures



Answered by Expert 16th January 2017, 12:11 PM
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