Category Archives: physics

the Gaussian beam (interactive)

The Gaussian beam “is a convenient, widespread model in laser optics.” [1] It is indeed convenient that such a mathematically relatively simple model can describe the evolution of laser light in free space so well. Given the wavelength of the laser, it can be described by a single parameter. This can be either the beam […]

the Doppler effect (relativistic)

Christian Doppler in 1942 predicted the Doppler effect for all kinds of waves, not only sound waves. The Doppler effect for light was demonstrated in 1948 by Fizeau. In conjunction with the article on the classical Doppler effect, as it occurs e.g. for sound waves, we will here examine the relativistic Doppler effect which is […]

the Doppler effect (classical)

The Doppler effect is nothing really new. It’s well-known that Doppler frequency shift occurs for sound as well as light; there are, however, some subtle differences between the two, owing mainly to Einstein’s special theory of relativity. This article describes the classical Doppler effect as it occurs e.g. for sound waves and in which the […]