Home made spectrophotometer for a laboratory bridging optics and modern physics

We present a simple methodology for measuring position and intensity in optic experiments by means of a CCD commercial camera or a cell-phone. The method employs digital photography and image processing techniques that can be used both in introductory physics laboratory and in high school. With the goal of bridging optics and modern physics, we designed low cost spectrometers based on the use of transmission diffraction gratings suitable for student’s lab work. This simple equipment was used to measure the wavelength of visible lines of Balmer series and estimate the value of Rydberg’s constant with a relative error of a few tenths of a percent. The method was also employed to evaluate Planck’s constant by measuring the wavelength of the light emitted by diodes corresponding to various colours. Finally, it was used to study some peculiar aspects of photoluminescence. The above experiments have been tested with high school students and with student teachers in a postgraduate course for physics teacher education. Our results indicated that the students were thoroughly satisfied and performed significant analysis on their data.