Isaac Newton is best known for his 3 laws of motion and of course gravity. However, he was one of the great scientists, with other great discoveries, among them the optical prismwhere he managed to decompose the light. The Newton's prism is probably one of the simplest tools of science we can learn from. Newton chose optics for his university lectures. In 1666 Newton succeeded in breaking down light into the colours of its spectrum by means of a prism, and in 1672 he presented to the Royal Society this new discovery.
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NEWTON PRISM: DECOMPOSITION OF LIGHT
Many of the scientists of the time thought that colour was a mixture of light and dark and that it was the prisms that coloured the light and therefore emitted it. Aristotle once wrote of white light as a single entity, but Newton was convinced that white light was a mixture of different colours.
The different colours that we can see are due to the different wavelengths of the components of light. When light is passed through a glass prism, due to the phenomenon of refraction when changing medium, each wavelength has a different deviation, separating into colours and giving all the colours that make up white light.
In his day, Newton did not work with wavelengths, since it was not known that light was a wave-particle. Today we know that not all wavelengths are visible to the human eye, and so there are non-visible radiations between 350nm and 740nm (infrared, below 350nm, to ultraviolet, above 750nm).
The same phenomenon of light decomposition that occurs in the optical prism occurs with water droplets suspended in the atmosphere, decomposing the light and resulting in rainbows.
To perform the experiments, Newton used two triangular optical prisms made of glass. With the first prism he separated the colours, and used a second prism to refract them back into white light. In this way Newton demonstrated that the colour was not generated by the prism, but was decomposed and could be rejoined in white light.
This discovery was a major contribution to our current understanding of light and colour, which was born with Isaac Newton.
VISIBLE LIGHT IN THE ELECTROMAGNETIC SPECTRUM
Visible light is composed of electromagnetic waves. It is part of the electromagnetic spectrum and is the area that the human eye is able to perceive. Each colour has a different wavelength. At one end of the visible light spectrum (above violet) would be ultraviolet light and at the other end (below red) would be infrared.
Read more about the electromagnetic spectrum at: Electromagnetic spectrum.
SUNLIGHT SPECTRUM
The spectrum of waves coming from the sun is not only the visible light waves that we see, from the sun we receive practically the entire electromagnetic spectrum. In the following map you can see the distribution of sunlight. As you can see, the highest intensity corresponds to the blue-green-yellow band, but we also find waves of shorter length than violet (ultraviolet rays) and above the red colour (infrared).
The amount of shorter wavelength waves than violet is quite substantial. It is the ultraviolet rays (especially the further away from the visible spectrum) that are most damaging to both eyesight and skin, hence the importance of using sun cream and sunglasses with good glass to protect against these rays.
Read more about the spectrum of sunlight at: Sunlight spectrum
BUY NEWTON PRISM
You can buy a Newton prism to break light into: https://amzn.to/2UVuxS4