The electromagnetic spectrum offers various ranges of colours that can be observed by the human eye. The visible spectrum ranges from 390 nanometers to 780 nanometers. Moreover, the electromagnetic spectrum has light frequencies that are either too low or too high for humans to see, for example, the ultraviolet that is located past the infrared, found in the red part of the visible light spectrum (Cao & Cui, 100)
Visible spectrum is a small part of the electromagnetic spectrum that can be observed by the human eyes. The frequency and the wavelength are often inversely proportional. A rise in frequency causes a decrease in wavelength as well as an increase in the energy associated with the photon. Radiations with longer wavelength, infrared and visible light are non-ionizing radiation because ionizing radiations entail UV light, gamma rays and X-rays. The limit between now- ionizing and ionizing radiation is found within the ultraviolet regions (Eugene Hecht, 50). Pure colours or spectra are those colours that are made up of only one wavelength. Visible wavelengths go through optical window which is defined as the region in the electromagnetic spectrum that permits wavelengths to go through the earth’s atmosphere.
The midday skies often appear blue as a result of clean air scattering it more than red wavelength. The optical window is also known as visible window. In the thirteenth century, Roger Bacon asserted that rainbows developed in the same way as light passing through a crystal or prism. Isaac Newton discovered that prisms could reassemble and disassemble white light and illustrated the finding in his books about optics. He observed that a fraction of beam of light is reflected while other fractions go through the prism when a narrow beam of light strikes the face of a glass prism (Eugene Hecht, 50). The beam of light that goes through the glass often appeared as colored bands. Newton hypothesized that light comprises of