Tracker is a piece of freeware software, designed to use video recorded images of the motion of objects as input data, and has been mostly applied in physics education to analyse and simulate physical phenomena in mechanics. In this work we report the application of Tracker to the study of experiments in electricity and magnetism using analog instruments for electrical signal measurements. As we are unable to directly video-track the motion of electrons in electric circuits, the angular deflections of the instruments’ pointers were video captured instead. The kinematic variables (angular position as a function of time) had to be related to the electrical ones (voltages and currents as a function of time). Two well-known experiments in physics teaching, the RC circuit for charging and discharging a capacitor and Faraday electromagnetic induction, were chosen to illustrate the procedures. The third experiment analysed and modeled with Tracker was the rather well-known electromagnetic retardation of disk- or cylinder-shaped magnets falling inside non-magnetic metallic pipes. Instead of metallic pipes we used an aluminum plate with an arrangement of a couple of parallelepiped-shaped magnets falling parallel to the plate. In the three cases studied, the experimental and the Tracker simulation results were in very good agreement. These outcomes show that it is possible to exploit the potential of Tracker software in areas other than mechanics, in areas where electrical signals are involved. The experiments are inexpensive and simple to perform, and are suitable for high school and introductory undergraduate courses in electricity, magnetism and electronics. We propose the use of Tracker combined with analog measuring devices to explore further its applications in electricity, magnetism, electronics and in other experimental sciences where electrical signals are involved.

The x-ray diffraction (XRD) technique has become an irreplaceable tool in the study of crystalline solids and is taught as part of the content of undergraduate solid state physics and chemistry courses. The XRD by crystalline materials is a scientific discovery predicted by von Laue, experimentally verified by Friedrich and Knipping and further developed by Bragg and Bragg, father and son, all in 1912. As a demonstration for students` experimental training, we have applied the XRD technique to determine structural and some structure-related properties (grain size, dislocation density, internal strain and stresses, bulk density) of two thin films, one with a tetragonal structure (TiO2) and the other with an hexagonal structure (ZnO). The students, in groups of three and two learned: to prepare TiO2 and ZnO thin films by the spray pyrolysis technique, to analyze diffractograms to obtain structural and some structural-based properties of the films. They had the opportunity to compare by themselves theory and experimental results. In this work, we combine one way of teaching well-established knowledge on XRD with a discussion on the nature of scientific discoveries pointing towards the identification of the individual abilities needed to be cultivated by the students as potential researchers. We discuss XRD by crystals as a scientific discovery highlighting the Laue and the Braggs different ways to think on the phenomenon (as diffraction and as reflection of waves). It is important to train and encourage students to find more than one way to think when dealing with scientific problem-solving.