Thermometry

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Thermometry

  1. 1. THERMOMETRY
  2. 2. INTRODUCTION
  3. 3. <ul><li> </li></ul><ul><ul><li> THAT DEALS WITH </li></ul></ul>MEASUREMENTS OF TEMPERATURE THERMOMETRY BRANCH OF SCIENCE
  4. 4. <ul><li>Is The Study Of …….. </li></ul><ul><li>-The Dynamic Relationship Between </li></ul><ul><li>Heat & Temperature </li></ul><ul><li>Thermal Properties Of Matter </li></ul><ul><li>And </li></ul><ul><li>- Processes Involving Heat Transfer </li></ul>THERMODYNAMICS
  5. 5. <ul><li>The history of thermometry starts around 1600 AD in </li></ul><ul><li>ITALY with the invention of AIR THERMOSCOPE . </li></ul><ul><li>LIQUID-IN-GLASS THERMOMETERS first appeared around 1650 AD . </li></ul><ul><li>By 1714 AD thermometers with MERCURY were found to give more LINEAR SCALES than SPIRITS . </li></ul><ul><li>The 19 th CENTURY saw many developments in thermometry … </li></ul><ul><li>e.g. ELECTRICALLY BASED TEMPERATURE SENSORS </li></ul><ul><li>such as </li></ul><ul><li> THERMOCOUPLES & RESISTANCE THERMOMETERS were invented for the measuring temperatures. </li></ul>THERMOMETRY
  6. 6. - a form of ENERGY - UN-ORGANISED KINETIC ENERGY of particles of a substance manifests itself in the form of heat - has the ability to do WORK HEAT
  7. 7. <ul><li>The DEGREE OF HOTNESS of a MATERIAL BODY </li></ul><ul><li>Determines … </li></ul><ul><li>DIRECTION OF TRANSMISSION of HEAT </li></ul><ul><li>Effect of … </li></ul><ul><li>INTER-MOLECULAR COLLISION </li></ul>TEMPERATURE
  8. 8. THE PROPERTY OF A SUBSTANCE SUITABLE FOR MEASURING TEMPERATURE THROUGH THEIR USE IN THERMOMETERS IS CALLED THE THERMOMETIC PROPERTY AND THE SUBSTANCE IS CALLED A THERMOMETRIC SUBSTANCE . SUCH A PROPERTY VARIES QUITE LINEARLY WITH TEMPERATURE OVER A REASONABLE RANGE OF TEMPERATURE. DEPENDING ON THE RANGE OF LINEARITY OF THE THERMOMETIC PROPERTY AND THE THERMOMETRIC SUBSTANCE USED, VARIOUS TYPES OF THERMOMETERS SUITABLE FOR MEASURING TEMPERATURE ACCURATELY OVER THE SAME RANGE ARE MANUFACTURED. THE RANGE OF LINEARITY OF THE THERMOMETRIC PROPERTY SELECTED FOR ITS USE IN A SPECIFIC THERMOMETER IS ALSO TERMED AS THE THERMOMETRIC RANGE OF THE THERMOMETER. THERMOMETRIC PROPERTIES OF SUBSTANCES
  9. 9. <ul><li>THERMOMETRIC PROPERTY </li></ul><ul><li> ‘ X’ </li></ul><ul><li>Ideal Behaviour Zone X 100 </li></ul><ul><li>Real Behaviour Zone </li></ul><ul><li>x t </li></ul><ul><li>X O </li></ul><ul><li>t1 deg C 0 deg C t deg C 100 deg C t2 deg C </li></ul><ul><li>TEMPERATURE ‘ t ’ in degree C </li></ul><ul><li>t = (X t- X 0 ) x 100 deg C </li></ul><ul><li>(X 100- X 0 ) </li></ul><ul><li>Thermometric range = (t1 - t2) </li></ul>THERMOMETRIC PROPERTY AND TEMPERATURE MEASUREMENT
  10. 10. MECHANICAL PROPERTIES LENGTH : VARIES LINEARLY WITH TEMPERATURE t = (Lt-L0)/(L100-L0) x 100 degree C Used in Liquid-in-glass thermometers PRESSURE : VARIES LINEARLY WITH TEMPERATURE t = (Pt-P0)/(P100-P0) x 100 degree C Used in Constant Volume Gas Thermometers VOLUME : VARIES LINEARLY WITH TEMPERATURE t = (Vt-V0)/(V100-V0) x 100 degree C Used in Constant Pressure Gas Thermometers THERMOMETRIC PROPERTIES OF SUBSTANCES
  11. 11. ELECTRICAL PROPERTIES ELECTRICAL RESISTANCE : VARIES LINEARLY WITH TEMPERATURE t = (Rt-R0)/(R100-R0) x 100 degree C Used in Platinum Resistance Thermometers THERMO-ELECTRIC EMF : VARIES NON-LINEARLY WITH TEMPERATURE HENCE APPROXIMATED BY A POLYNOMIAL EQUATION PECULIAR TO THE THERMO-COUPLE THERMOMETRIC PROPERTIES OF SUBSTANCES
  12. 12. COMPARISION OF THERMOMETERS
  13. 13. TYPES OF THERMOMETERS <ul><li>Liquid-in-glass thermometers </li></ul><ul><li>Constant Volume Gas Thermometers </li></ul><ul><li>Constant Pressure Gas Thermometers </li></ul><ul><li>Platinum Resistance Thermometers </li></ul><ul><li>Thermo-couples </li></ul><ul><li>Radiation Thermometers </li></ul>
  14. 14. Liquid-in-glass Thermometers <ul><li>Mercury Thermometer </li></ul>
  15. 15. Liquid-in-glass Thermometers <ul><li>Alcohol Thermometer </li></ul>
  16. 16. Liquid-in-glass Thermometers <ul><li>Six’s </li></ul><ul><li>Maximum-Minimum </li></ul><ul><li>Thermometer </li></ul>
  17. 17. THERMO-COUPLES
  18. 18. RADIATION THERMOMETERS

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