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Al Tobias (wat4y) - Office: Gibson S123 & Physics 218, (434) 924-0538

Physics Demo Manual

Demonstrations are cataloged according to PIRA Bibliography


Due to Physics Building renovations, the lead time to set up demo requests has increased due to the need to transport equipment across campus. Please be kind and let me know well ahead of time what you need.

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 Thermal Properties Of Matter
 Heat And The First Law
 Change Of State
 Ice Bomb (expansion of water upon freezing)
 Regelation in Ice
  video  - Thermocouple in Ice
  video  - Boiling by Cooling
  video  - Boiling by Reducing Pressure
  video  - Crush the Soda Can
 Sling Psychrometer (Relative Humidity)
 Phase Change in Iron
 Kinetic Theory
 Gas Law
 Entropy And The Second Law

 video  - Boiling by Reducing Pressure


To show that the boiling point of a liquid, in this case water, depends on pressure as well as temperature.


centered image

Fill the cold trap on the vacuum pump inlet port with liquid nitrogen (LN2) to prevent water vapor from entering the pump and spoiling the oil. Turn ON the pump and the water will begin to boil once the pressure drops close to vacuum.


You might want to move the vacuum chamber off the pump cart to avoid the vibrations of the water beaker. This way the water disturbance due to boiling is more sudden and dramatic.
Few neat tricks can be demonstrated.The lecturer can pressurize the chamber quickly and pull the beaker out to stick the finger into "boiling" water.
Continuous pumping is actually cooling by evaporation and the water actually keeps getting colder. This can be demonstrated by measuring the temperature of water before and immediately after the pumping.


  • Beaker of water
  • Vaccum Pump