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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
 Kinetic Theory
 Gas Law
 Entropy And The Second Law
  video  - Reversible and Irreversible Processes
  video  - Stirling Engine
  video  - Steam Engine
 Heat Engines

 video  - Steam Engine


To show the operation of a steam engine and how the energy produced may be turned to useful work.


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  DEMO VIDEO DOWNLOAD w/ sound / 1920x1080 / 24.19Mb/s / 359MB size  

  DEMO VIDEO DOWNLOAD w/ sound / 854x480 / 5.69Mb/s / 88MB size  

We have two working Jensen steam engines, each has a single-acting cylinder but the boiler is heated with burning gas in one version, an electric heater in the other. In a single-acting cylinder, the steam pushes on one side of the piston only. The cylinder depends on the load, springs, other cylinders, or the momentum of a flywheel, to push the piston back in the other direction.

JENSEN MODEL 60 GAS FIRED BOILER: (first image) Open whistle to vent air. Fill the boiler chamber with distilled water until the view window shows the chamber is about half full. Connect rubber tubing to gas source under lecture bench. Open bench valve to allow small amount of gas through (do not touch gas line valves on engine board, they have been preset). Ignite and let water heat. Approximately five minutes is needed for the engine to work properly. The hammer will strike and the steam whistle works. Jensen instruction manual is here.

JENSEN MODEL 70 ELECTRIC HEATED BOILER: (second image) Jensen instruction manual is here.


We also have a Welch Scientific model of a double-acting cylinder steam engine (last image). You turn a crank to show its operation. The lever changes the valves orientation for forward vs. reverse operation.


  • Matches
  • Miniature steam engine
  • Rubber Tubing
  • Water