How to build a low cost spectrometer with<i>Tracker</i>for teaching light spectra

Optics is probably one on the most exciting topics in physics. However, it also contains some of the less understood phenomena by students—the light spectra obtained from the diffraction of light. The experimental study of light spectra for studying radiating bodies, usually requests sophisticated and expensive equipment that is not normaly affordable for schools, and only a few teachers know how to measure the wavelength of light in a spectrum. In this work we present a simple and inexpensive setup, with enough accuracy for measuring light spectra to be used both in physics and chemistry classes. We show how freeware software Tracker, commonly used for teaching mechanics, can serve to measure wavelengths with about 2 nm of resolution. Several approaches to the calibration of different setups are also provided, depending on the degree of accuracy demanded.