PASCO OS-8539 Educational Spectrophotometer - Manual (Page 27)

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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
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Teacher’s Guide
Activity 1: Emission (Bright Line) Spectrum
Notes
1. A mercury vapor light source may take up to 20 minutes to warm up, so it is a good idea to turn it on as soon
as possible.
2. 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.
3. 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.
Sample Data
Five of the seven lines of color for mercury vapor are shown in the example. The blue-green line is more promi-
nent on both sides of the central ray when the GAIN select switch on the High Sensitivity Sensor is set to 100.
Data Table
Color 
1

2
   d sin
yellow 0.7808 0.0692 0.7116 0.3558 580.0 nm
green 0.7613 0.0887 0.6726 0.3363 549.0 nm
blue-green 0.3016 494.8 nm
blue 0.6908 0.1578 0.5330 0.2665 438.0 nm
violet 0.6712 0.1773 0.4939 0.2469 407.1 nm
Conclusion
Compare your values for the wavelengths of color in the mercury vapor light spectrum to the accepted values for
wavelengths.
Color yellow 2 yellow 1 green blue-green blue violet 2 violet 1
 579.0 577.0 546.1 491.6 435.8 407.8 404.7
Extensions
Repeat the process for a different gaseous element, such as hydrogen or helium.