Physics · Ch 6 — Optics
Dispersion of White Light through Prism
Dispersion of White Light through Prism
When white light passes through a prism, dispersion occurs -- the splitting of white light into its constituent colours (a spectrum), because the refractive index of the prism material (and hence the deviation it produces) is slightly different for each colour. A narrow beam of white light incident on a prism emerges as a fan of colours in the order recalled by VIBGYOR: Violet, Indigo, Blue, Green, Yellow, Orange, Red, with violet deviated the most and red deviated the least. Different colours are associated with different wavelengths, red at the longer-wavelength end (about 700 nm) and violet at the shorter-wavelength end (about 400 nm); since the violet ray travels slower inside a glass prism than the red ray, violet has the higher refractive index of the two and is bent more. …
What this figure shows. A narrow beam of white light enters a prism and emerges spread out into a fan of separately-coloured rays striking a screen in the order Violet, Indigo, Blue, Green, Yellow, Orange, Red (VIBGYOR), with violet deviated through the largest angle and red through the smallest. This spread happens because the prism material's refractive index is not quite the same for every wavelength -- it is highest for the shortest-wavelength violet light and lowest for the longest-wavelength red light -- so each colour follows a very slightly dif …