PASCO TD-8580A Thermal Cavity - Manual (Page 6)

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Thermal Cavity Suggested Experiments
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6. Connect the Light, Thermistor, and Rotary Motion sensors to the interface (or
interfaces). 3 Leave the IR Sensor unconnected for now.
7. In DataStudio, start data monitoring (open the Experiment menu and select Mon-
itor Data). The measured cube temperature will appear in the digits display.
8. Turn on the power supply and set the voltage to 10 V. When the cube temperature
reaches about 80 °C, set the voltage to about 7 V. Allow the temperature to stabi-
lize between 80 and 100 °C before proceding.
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Procedure
1. Move the Light Sensor to one end of the Linear Translator.
2. Click Stop to stop data monitoring, then Click Start to start data recording.
3. Move the Light Sensor at a slow, steady pace across the Linear Translator to scan
the cavity side of the cube. Click Stop.
Observe the graph of Visible Light Intensity versus Position. If necessary, delete
the data
5 and repeat this step to obtain a satisfactory graph.
4. Remove the Light Sensor from the Aperture Bracket and replace it with the IR
Sensor. Connect the IR Sensor to the interface. 6
5. Move the IR Sensor to one end of the Linear Translator.
6. Click Start.
7. Move the IR Sensor at a slow, steady pace across the Linear Translator to scan
the cavity side of the cube. Click Stop.
Observe the graph of IR Light Intensity versus Position. If necessary, delete the
data and repeat this step to obtain a satisfactory graph.
8. Turn off power to the Thermal Cavity.
Analysis
1. Compare the graphs of visible and IR light intensity. Which graph displays
reflected light and which displays emitted radiation?
2. When you look at the cavity, does it appear lighter or darker than the surrounding
cube surface? How is the appearance of the cavity represented in the graph of vis-
ible light intensity?
3. Allow the cube to cool to room temperature, then remove the cap from the top of
the cube. Does the inner surface of the cavity appear lighter or darker than outer
surface of the cube?
4. In the infrared region of the spectrum, was the cavity brighter or darker than the
cube surface?
5. Compare the emitted radiation of the cavity and the cube surface. Which source
of radiation has the higher emissivity?
3 If you are using a
ScienceWorkshop inter-
face, refer to the
DataStudio configuration
file for sensor gain set-
tings and channel asign-
ments.
4 If you are using a Power
Amplifier, the power turns
on automatically when-
ever data is being moni-
tored or recorded. The
temperature is thermo-
statically set for 80 °C.
Turn on data monitoring
between data-recording
runs to keep the cube
hot.
5 Open the Experiment
menu and select Delete
Last Run.
6 If you are using a Power
Amplifier and a
ScienceWorkshop inter-
face, disconnect the
Light Sensor from Chan-
nel A and replace it with
the IR Sensor.