This note describes an alternative classroom demonstration of Newton’s classic method to mix, by means of a prism, rainbow colours to get white light again. […]
Following a high-school teaching method we propose the subject-matters used in 1905 by A. Einstein to explain the relativistic effect of a magnetic field. Following the Lorentz-Einstein transforms in time and space, we show that what appears as an electric field in an inertial reference system can be seen in another relativistically equivalent system as a magnetic field. […]