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.

 Choose a Topic or Enter a keyword to search: I cannot find what I want! You have selected the following Demos: None Selected

Choose a subtopic:
Thermal Properties Of Matter
Heat And The First Law
Calorimeter
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

### Leslie Cube

#### Purpose:

An illustration of radiative heat transfer where the heat energy radiated from surfaces at the same temperature but with different emissivities is compared.

#### Procedure:

Connect the Thermopile to the current amplifier and the amplifier to the LED bar graph meter. The Leslie cube should have been turned on at the beginning of class so be careful as the surfaces could be very hot. Rotate the cube so that different surfaces are facing the cube making sure to keep the distance from the cube to the thermopile constant. The bar graph will give a reading such that the number of lit led's is approximately proportional to the amount of heat energy hitting the thermopile. The black surface radiates the most energy, followed by the white surface (which, as it turns out is fairly black in the infrared region), the gray surface and the silvered surface in order of decreasing heat energy radiated. You can also place your hand or other objects in front of the thermopile to see how much heat is given off.

#### Hints:

Current amplifier settings that have worked in the past:
• Gain = 105 V/A
• Suppression = 10-7 A
• Polarity = +
• Rise Time = 0.03 ms