Lab: Spectrometry

Goal: To observe several spectra.

Materials (available from educational or science supply stores)

Prism
Diffraction grating
Colored cellophane
Paper or plastic tube

Procedure

If you do not have a spectrometer in your lab kit, follow the instructions to build a homemade spectrometer here. Create a provisional scale, recognizing that red light to purple light spans the range 400nm to 700nm roughly.
With your spectrometer (homemade or from the kit), view at least four of the following

Household incandescent light bulb
Fluorescent bulb
Yellow (sulfur) street lights
Blue/white (mercury) street light
Sunlight reflected off a sull white surface (e.g., a cloth sheet or piece of paper)
"Neon" shop signs of different colors [Red ones are likely to actually be neon; other colors use other gases)

Data Handling

Use the wavelength scale to estimate the position of the emission spectrum lines.
Use the pattern of lines to identify the type of material from which they come for each of your observations.
Refine your scale based on known wavelengths of the specific elements you observe.

Report

Describe your materials, equipment, and procedures in sufficient detail that your fellow students could repeat your experiment.
Report your data. Be sure to indicate the amount of error in your measurements. For example, if you can only measure a wavelength to within 10nm, your values should read "400nm ± 10", or 10/400 = 2.5%.
Present your data in an organized form, preferably in a table, in such a way it is easy to compare results as you repeat trials or vary a specific contributing factor.
Show a sample calculation, if you have calculated values.
If you did a series of experiments, varying something by increasing or decreasing a factor, try to plot your data (y-axis) as a function of the factor (x-axis).
You may use a spreadsheet to calculate your information and create your table.
Summarize your results.
Draw conclusions about what is happening.
Suggest at least one way to improve your experiment.

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