Al Tobias (wat4y) - Office: Gibson S123 & Physics 218, (434) 924-0538
Demonstrations are cataloged according to PIRA Bibliography
PLEASE REQUEST DEMOS WELL IN ADVANCE
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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You have selected the following Demos:
Jug O' Air
Purpose:An illustration of adiabatic cooling.
Procedure:A thermistor connected to a multimeter (LED bar) gives an indication of the temperature inside the jug measured in Fahrenheit (relative). Plug the jug with the rubber stopper and pump air into the jug. The increase in pressure is associated with a rise in temperature of the air in the jug. Keep pumping until the cork pops off the jug. The air in the jug will go through a period of rapid cooling as seen on the meter. The air will actually cool to a lower temperature than it started with.
Hints:When using the LED bar, make sure the polarity of the voltage signal going into the LED bar is positive (you may adjust the leads at the thermistor circuit). The following amplifier settings has worked in the past:
Keithley 427 Current Amplifier