PASCO OS-8539 Educational Spectrophotometer - Manual (Page 11)

®
M o d e l N o . O S - 8 5 3 7 a n d O S - 8 5 3 9 S e t U p
7
4. In the data acquisition program, use the
built-in Calculator to create a calculation.
Base the calculation on the “Angular Posi-
tion” measurement from the Rotary Motion
Sensor. In the calculation, divide “Angular
Position” by 2
where  is approximately
3.1416… Label your calculation “Ratio of
Radii” (see Fig. 9).
5. In the program, select a Graph display and set
it to show the calculation “Ratio of Radii” on
its vertical axis.
6. Start recording data. Turn the Degree Plate in one direction slowly and continuously for exactly one com-
plete rotation. Stop recording data.
7. In the Graph display, use the built-in Statistics tools
to find the maximum value of the “Ratio of Radii”
(i.e., the maximum of y - see Fig. 10). This value is
the exact ratio of the Degree Plate radius to the small
Pinion post radius. (Note: This value should be close
to 60.) Record the actual ratio.
Ratio of Radii = _______
8. Replace the Light Sensor Arm on the Degree Plate
and fasten it to the plate with the two small thumb-
screws.
Mounting the Aperture Bracket Light Sensor Mount and Light Sensor
The Aperture Bracket has two main parts: the Light Sensor Mount
and the Holder. (The Holder and thumbscrew are not used and can
be put aside.) An Aperture Disk and Aperture Screen) are attached
to the front of the Light Sensor Mount.
The Light Sensor Mount has two holes: one hole in the center of the
mount and a second hole at the rear of the mount. The end of the
Light Sensor Arm has three holes: two holes along the centerline of
the arm and one hole to the side of the centerline. Line up the center
hole of the Light Sensor Mount with the centerline hole in the Light
Sensor Arm that is closest to the Degree Plate.
Line up the High Sensitivity Light Sensor so the threaded hole in its
base is above the center hole of the Light Sensor Mount. Use the
threaded post (included with the Aperture Bracket fasten the High
Sensitivity Light Sensor and Light Sensor Mount to the Light Sen-
sor Arm (Fig. 11).
Rotate the Aperture Disk on the front of the Light Sensor Mount so
that the narrowest slit is in line with the opening to the sensor.
Connect the High Sensitivity Light Sensor to the PASCO interface.
Figure 9: Calculation of Ratio of Radii
NOTE: The
calculator in
your program
may differ in
appearance.
Refer to your
User’s Guide.
NOTE: The
Graph display in
your program
may differ in
appearance.
Refer to your
User’s Guide.
Figure 10: Sample Degree Plate Calibration Data
HIGH SENSITIVITY
LIGHT SENSOR
CI-6604
Figure 11: Sensor and Aperture Bracket
onto Light Sensor Arm
Aperture
Bracket Light
Sensor Mount
Light Sensor
Arm
High Sensitivity
Light Sensor
Threaded post