PASCO OS-8539 Educational Spectrophotometer - Manual (Page 29)

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M o d e l N o . O S - 8 5 3 7 a n d O S - 8 5 3 9 T e a c h e r ’ s G u i d e ( C o n t i n u e d )
25
Teacher’s Guide (Continued)
Activity 2: Absorption (Dark Line) Spectrum
Notes
1. The light source from the PASCO Introductory Optics System or the light source from the PASCO Basic
Optics System can be used as the incandescent source.
2. The liquid sample should be dilute enough to see through.
3. Suggestions for calibrating the Degree Plate with the small post of the Pinion and for calibrating the Grating
are given in the Set Up section of the manual.
4. Depending on which way the Degree Plate is turned, the Angular Position data from the Rotary Motion Sen-
sor may go in the negative direction rather than the positive direction along the horizontal axis of the Graph
display. If this occurs, switch the two plugs on the end of the sensor’s cable.
Questions
1. What color corresponds to the wavelength for each “dark line” in your absorption spectrum?
Answers will vary.
2. How does the color or colors that are absorbed out of the continuous spectrum compare to the naked eye
color of your liquid sample?
Answers will vary
Extensions
Repeat the process for a different liquid sample, such as chlorophyll extracted from a spinach leaf.
Sample Data
Figure TG-3: Example of Absorption Spectrum
for Food Coloring
Figure TG-4: Example of Absorption Spectrum
for a Green Leaf
continuous
spectrum
continuous
spectrum
absorption
spectrum
absorption
spectrum