Question

Why does violet colour deviate most and red deviate the less

Answer 1

Violet colour deviate most and red deviate the less because the wavelength of a red light is almost double the wavelength of violet light.
Because of the different indices of refraction for the different wavelengths of visible light, the angle of deviation varies with wavelength. But since the violet light has a shorter wavelength, it would refract more than the longer wavelength red light.
Hope it helps❤️❤️❤️

Answer 2

Hello Utsav!
first to answer your query we need to know about 2 most imp. things which when understand can help you solve any kind of question like this.
these things are .. 1. Rayleigh scattering law.
it simply states that u ( Refractive index) is inversely proportional to square of the wavelength of light.
2. deviation is directly related to refractive index.
More the index more will be the deviation.

now you know red light has large wavelength and violet has less .so refractive index of red will be smaller than that of violet . and hence smaller the index smaller will be deviation so red light deviates less as compared to violet.
Thank you for reading!..