When a beam of white light is allowed to fall on a prism, the maximum

When a beam of white light is allowed to fall on a prism, the maximum deviation of the emerging light occurs for

red light
violet light
yellow light
blue light
This question was previously asked in
UPSC CAPF – 2019
The correct answer is B) violet light.
When a beam of white light passes through a prism, it undergoes dispersion, splitting into its constituent colours (spectrum: Violet, Indigo, Blue, Green, Yellow, Orange, Red – VIBGYOR). This happens because the refractive index of the prism material is different for different wavelengths (colours) of light.

* Refraction is the bending of light as it passes from one medium to another. The amount of bending depends on the refractive index of the medium and the angle of incidence.
* For visible light passing through a prism, the refractive index of the prism material is higher for shorter wavelengths and lower for longer wavelengths.
* Violet light has the shortest wavelength among the colours in the visible spectrum.
* Red light has the longest wavelength among the colours in the visible spectrum.
* Since the refractive index is highest for violet light, it is bent the most (deviated the maximum) when passing through the prism.
* Conversely, since the refractive index is lowest for red light, it is bent the least (deviated the minimum).

The order of deviation from maximum to minimum is typically Violet > Indigo > Blue > Green > Yellow > Orange > Red.

This phenomenon of dispersion is described by Cauchy’s equation, which relates the refractive index of a material to the wavelength of light. This effect is responsible for the formation of rainbows, where raindrops act like tiny prisms, dispersing sunlight.