2015 BFY II Abstract Detail Page
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||W14 - Shoebox Spectrographs (Low-Cost Light and Spectroscopy Experiments)
||Spectrographs (a device used to take pictures of spectra) are typically expensive and fragile. Because of the cost and fragility of these devices, most student investigations that use spectrographs have restrictive instructions that can limit student discovery and experimentation. The shoebox spectrograph is quite different. It is made of scrap corrugated cardboard, a DVD disc fragment, lots of duct tape, school glue, and a cheap camera (we usually use a $30 webcam but a camera on a phone will also work). Despite using low quality components, the shoebox spectrograph can be remarkably accurate. A well-constructed shoebox spectrograph can resolve spectral lines that are ~2 nanometers apart and can identify unknown spectral lines to within a nanometer. We have found that shoebox spectrographs are easily constructed (our students build their own), versatile and durable enough to allow students to independently explore light phenomena for a variety of experiments.
One of the most obvious investigations is to have students examine atomic light sources (power supply ~ $160 and gas tubes ~$50 each). These experiments are also the easiest way to calibrate and determine the relative accuracy of an individual spectrograph. However, one can do a lot of experiments without atomic light sources. For example, one can record sunlight spectra which will include the Fraunhofer absorption lines (which can also be used for calibration). If one procures an ordinary gooseneck desk lamp (~$30), students can perform low cost transmission and reflection experiments (including dandelion flower reflection spectroscopy). One of our favorite alternate experiments is an examination of laser induced fluorescence of Play Doh. This requires red, green, and blue "laser pointers" (~$7 per color laser) and a variety pack of Play Doh (20 color pack is ~ $12).
In fairness, there is an assumed equipment list. One will need access to a computer with a spreadsheet program and ImageJ (a free downloadable program). It is also assumed that one has a few basic tools (box cutter, shears, ruler, and meter stick). Heat guns are most convenient for producing DVD fragments, but tongs and a boiling pot of water can be used if a heat gun isn't available.
Attendees of this workshop will construct their own spectrographs out of pre-cut cardboard and learn how to calibrate and use them. Then a single experiment will be done such as laser induced fluorescence of Play Doh.
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