PASCO OS-8539 Educational Spectrophotometer - Manual (Page 20)

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E d u c a t i o n a l S p e c t r o p h o t o m e t e r A c c e s s o r y K i t a n d S y s t e m A c t i v i t y 1 : E m i s s i o n ( B r i g h t
16
Procedure
In this activity, the High Sensitivity Light Sensor measures the relative intensity of colors of light in an emission
spectrum produced by light from a mercury vapor light source passing through a grating. The Rotary Motion
Sensor measures the angle,
, of each band or “bright line” of color.
The data acquisition program records and displays the light intensity and the angle. You can use the program’s
built-in data analysis tools to find the angle for each color, and then you can determine the wavelength,
, of each
color.
Equipment Setup
1. Set up the Spectrophotometer next to a
mercury vapor light source as shown
(Fig. 1.2). If needed, use the Rod
Stand Mounting Clamps, two rods,
and two bases to raise the Spectropho-
tometer to the same level as the open-
ing to the light source. (Refer to the
Introduction for more information.)
2. If the light source has a large opening,
mask the opening so it transmits a nar-
row (0.5 to 1.0 cm) beam to the Colli-
mating Slits. Put a cloth hood over the
light source and attach the edge of the
hood to the plate on the Collimating Slits.
3. Turn on the light source. Once it is warmed up, adjust the light source, Collimating Slits, Collimating Lens,
and Focusing Lens so clear images of the central ray and the first order spectral lines appear on the Aperture
Disk and Aperture Screen in front of the High Sensitivity Light Sensor. Turn the Aperture Disk so the small-
est slit on the disk is in line with the central ray.
4. Connect the PASCO interface to the computer, and turn on the interface. Start the data acquisition software.
5. Connect the High Sensitivity Light Sensor cable to Analog Channel A. Connect the Rotary Motion Sensor
cable to Digital Channels 1 and 2.
Experiment Setup
Select the Sensors, Set the Sample Rate, and Create a Calculation
Refer to the User’s Guide for your version of data acquisition software for detailed information on selecting sensors, changing the
sample rate, and creating a calculation.
1. In the program, select the Rotary Motion Sensor and connect it to Digital Channels 1 and 2 and select the
Light Sensor and connect it to Analog Channel A.
2. In the program, set up the Rotary Motion Sensor for high reso-
lution (1440 Divisions per Rotation) and set the sample rate to
20 Hz, or 20 measurements per second.
3. In the data acquisition program, use the Calculator to create a
calculation of Actual Angular Position based on the Angular
Position measurement made by the Rotary Motion Sensor and
the ratio of the radius of the Spectrophotometer’s Degree Plate
to the radius of the small post on the Pinion (Fig. 1.3). (Refer to
the Set Up section for more information.)
CI-6604A
PASCO scientific
HIGH SENSITIVITY LIGHT SENSOR
Light
source
Cloth hood
Collimating
Slits
Collimating
Lens
Grating
Rotary Motion
Sensor
Focusing
Lens
Light
Sensor
Base
Rod
Bench
Figure 1.2: Equipment Setup
Figure 1.3: Create a Calculation