Optics 4 - Dispersion of Light - PDF

7.4 Optics 7.4.5 Dispersion When a beam of white light (e.g. sunlight) passes through a prism, it is spread out by the prism into seven colours: Red Orange Yellow Green Blue Indigo Violet Richard of York Gave Battle in Vain The band of colo...

7.4 Optics 7.4.5 Dispersion When a beam of white light (e.g. sunlight) passes through a prism, it is spread out by the prism into seven colours: Red Orange Yellow Green Blue Indigo Violet Richard of York Gave Battle in Vain The band of colours is called a spectrum and the separation of the colours by the prism is known as dispersion. The separation of white light into its seven different colours is known as dispersion. Figure 20 shows white light incident on a prism. Refraction occurs at the air/glass boundary on entry, i.e. light bends towards the normal. Once inside the prism, the white light is dispersed into its seven colours, which are all refracted at the glass/air boundary at different angles. Light, here, is refracted away from the normal. Figure 20 L. BONELLO 23 7.4 Optics Each colour has its own frequency and wavelength. One notices that red is deviated the least by the prism whereas violet is deviated the most as can be seen in figure 21. Figure 21 Red – refracted the least, greatest wavelength Violet – refracted the most, smallest wavelength L. BONELLO 24