The Newton's disc!

Today I had a conference in which my classmates and me explained various experiments in physics

The tool, didactically very effective in its simplicity, had the task of demonstrating that white light is formed by the fusion of colors (wavelengths) that make up the spectrum of light, colors that can be obtained by means of a prism. This is what Isaac Newton (1642 - 1727) demonstrated in 1666 with experiments on the decomposition and recomposition of sunlight, hence the name of the device.

By turning the disc sufficiently fast, it turned white, although it was formed by differently colored sectors. When you fix a light source, the image imprinted on the retina (light-sensitive part of the eye) stays there for some time even after you have looked away from the source. The phenomenon is called persistence of the retinal image.

In the case of the disk each color impressed the retina and the stimulus remained even after the color that had produced it was replaced by another color. The result was the fusion of all the colors of the disc at the level of the retina and consequently the brain interpreted the information received as those produced by the "color" sum of all those that form sunlight and therefore the disk appeared white, although obviously it is not. Cinema (but not only) exploits the phenomenon of the persistence of the retinal image (Paxinoscope).