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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
 Heat Capacity using Wax and metal Balls
  video  - Convection Box
 Convection Chimney
 Chimney with Vane
  video  - Heat Conduction
  video  - Thermal Conductivity
  video  - Light The Match
 Leslie Cube
 Boiling Water in a Paper Cup
 Steam Gun
  video  - Fire Syringe
 Jug O' Air
 Change Of State
 Kinetic Theory
 Gas Law
 Entropy And The Second Law

 video  - Light The Match


To show that thermal radiation is emmitted from a hot object and that this radiation can be reflected and focused in the same way as visible light.


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  DEMO VIDEO DOWNLOAD / no audio / 1920x1080 / 24.19Mb/s / 331MB size  

  DEMO VIDEO DOWNLOAD / no audio / 854x480 / 5.69Mb/s / 75MB size  

Place the lamp at the focus of the source mirror and insert a match (with the end colored black with a Sharpie) in the holder attached to the target mirror. When the light is turned on, the match will flame up (typically within 10 to 30 seconds).


Lining up both mirrors is straightforward:
  • make sure match tip is marked black with a Sharpie pen so IR radiation is more efficiently absorbed
  • set 1000 Watt projector bulb 10.5cm from center of source mirror
  • set match holder 40cm from center of target mirror
  • turn on 1000 Watt projector bulb and move source mirror from side to side until it looks roughly aimed to the center of the target mirror
  • using a white sheet of paper, look at the light focus spot at the match holder
  • move target mirror from side to side and/or up and down until the focus spot on the paper lines up with the tip of the match in holder
  • fine adjusting the focus by moving the 1000 Watt projector bulb back and forward at the source mirror can increase the speed at which the match will burst into flames
In general, use the reflection in the mirror itself. To make sure the match head is lined up properly, look beyond the match head at the reflection in the mirror. The match head should be centered in the image of the opposing reflector. Use the same method for lining up the projector bulb in the other mirror.


  • Matches
  • Stand
  • Large Concave Mirrors
  • Heater Coil