Light is an electromagnetic wave. Its spectrum reaches from infrared, a wavelength longer than visible light, all the way to the x-ray region. The only range of light visible to the human eye is very small: wavelengths between around 700 and 400 nanometres – from red to ultraviolet light. If we allow light to fall on a prism, we can look through the light refraction and see the colour spectrum. Alternatively, we can bring together red, green and blue light. Our brain sees the mixture as “white light”. This is the basis of display technology.

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