The Prism

The prism, is a polyhedron formed by glass and delimited by flat and parallel faces. At the beginning, this was a children´s toy in the Newton´s time (he was a creative scientist and one the most complete in the history).

Over time, the cylinder has become a very important object in the world of the optics, thanks to Newton´s experiment.

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Figure 1. Triangular prism.

During the 17^th century, many researchers focused on the light subject. One of them, Descartes was convinced that the light was composed by corpuscles. He assumed that the colors were a proportion of the mix of light and dark too. So, he attempt to decompose light to get colors, but he only achieved the extreme colors (Red and Blue).

Newton, with a cheap experiment, obtained the decomposition of white light in colors and the reconstruction of it. For this, his experiment consisted of:

Figure 2. Newton´s experiment

 In a dark room, he let enter a ray of light, through a hole, that impinges on the prism placed at a certain distance. Once it passes through that object, the refraction of light occurs and with it the colors decomposition.

For the inverse demonstration, it was only necessary to place another prism in which these colors are incited; and to observe the white light at the exit.

Newton presented it at the Royal Society, where it caused a great sensation (Prism operation is similar to water droplets with the rainbow).

Today, prisms are used in optics to study the properties of light, optical montages, astronomy,etc...

There are only two types of prisms: the reflective and the refractive one. The first one have the function of reflecting light light and are used in instruments as well known as monoculars and binoculars. The dispersives (refractive) allow to achieve the decomposition of light in the spectrum of colors, being used in instruments like the oscilloscope to study the same one.

After reading this article, you will miss how to get a prism and test the idea that Newton had. As it is simple to make, it is only enough to make a cube from a glass or material with refractive power (like the water). However, for a better observation it is required of pure glass.

The prisms that are used in optics are more complex because they require cating processes and the material assembly.

Until the next time!.

Bibliography:

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