PASCO OS-8542 BLACK BODY LIGHT SOURCE - Manual (Page 12)

Black Body Instruction Manual 012-07105B
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**IMPORTANT OPERATIONAL NOTES**
The following notes are critical to maintaining the accuracy of the calibrations and experiment:
Setting the Collimating Slits - For best results, match the slit width size on the collimating lens to the
same slit width size on the aperture. For example, if you select the number 4 width from the collimat-
ing slits, select the number 4 width on the aperture. (For more information about adjusting the
collimating slits, see the Instructional Manual for the Model OS-8539 Educational Spectrophotom-
eter.)
Ensure the slit opening on the aperture slides directly over the hole on the back of the aperture
bracket; otherwise light will not reach the light sensor.
Adjusting the Voltage in the Black Body Light Source - In DataStudio, set the voltage in the Signal
Generator box. The recommended voltage setting is 7 volts. The voltage can be varied from zero to
10V, but continuous operation of the bulb at 10V will result in a shorter bulb life.
In DataStudio, display the temperature graph and ensure the voltage increase corresponds to a tem-
perature increase. The sampling rate is set to 50 Hz. Also, in DataStudio, ensure that you have
selected DC voltage in the Signal Generator box; do not select sine wave or another function. The
black body experiment requires direct and continuous current, not alternating or pulsating current.
To improve the voltage signal display on the graphs, increase the gain on the light sensor to 10 or
100. In the Signal Generator window, use the arrow keys to adjust the gain.
Checking the position of the prism - The prism mount and prism must remain fixed at all times. If
not, your data will be in error. If the prism mount rotates at any time during the scanning, discard the
data, recalibrate, and take another reading.
Checking the angular display against the reading on the degree plate - DataStudio allows you to
adjust the angle units to either degree or radians. If you set the units to rads in DataStudio, remember
that the number on the degree plate will not correspond to the number on the display. You will need
to mathematically convert degrees to radians.
If you have negative angle readings, you may have reversed the colored cables for the rotary motion
sensor, rotated the degree plate in the wrong direction, or improperly mounted the light sensor arm
and lenses. While taking a reading, the degree plate must rotate clockwise. For more information
about the rotary motion sensor or the light sensor arm, see the instruction manual for the Educational
Spectrophotometer.
From the “Displays” list, doubleclick on a graph icon. Drag and drop a voltage icon over the y-axis
label on the graph. Drag and drop a angular position icon over the x-axis label on the graph. (For
more detailed information about DataStudio, refer to the DataStudio online help guide listed under
the HELP menu in the software.)
Example: Generate a graph display of light intensity vs. angular position.
Note: If your graph displays negative angles, try reversing the position of the black and yellow
cables you have inserted into channels 1 and 2.