This note describes a simple demonstration of Rayleigh scattering1 that explicitly demonstrates the wavelength dependence as well as the full white light effect that produces the red of sunset. The interested reader can find a variety of other Rayleigh scattering demonstrations2–4 in the literature, including a nice summary article in this journal by Chiaverina5 in 2021. I have previously used a vertical version of the milk/coffee creamer2 method in my labs because the (then) horizontally scattered light is also horizontally polarized. In my laboratory case, students view the sunset aspect by looking at a mirror placed above the graduated cylinder, where the transmitted light is distinctly tinted red.
To get the wavelength-dependent features noted above, the demonstration version uses transparent 1/4-in.-diameter urethane rubber belting material6 as a light pipe (Fig. 1). However, the material also has small scattering centers, so that a diffuse glow...
