Explain the refractive index for light of different colours.

(N/A) Each colour is associated with a specific wavelength of light.
In the visible spectrum, red light is at the long-wavelength end $(\sim 700 \, nm)$, while violet light is at the short-wavelength end $(\sim 400 \, nm)$.
Dispersion occurs because the refractive index of a medium is different for different wavelengths (colours).
For example, the bending (deviation) of the red component of white light is the least, while it is the most for the violet component.
Equivalently, red light travels faster than violet light in a glass prism.
The table below provides the refractive indices for different wavelengths for crown glass and flint glass:

Colour	Wavelength $(nm)$	Crown glass	Flint glass
Violet	$396.9$	$1.533$	$1.663$
Blue	$486.1$	$1.523$	$1.639$
Yellow	$589.3$	$1.517$	$1.627$
Red	$656.3$	$1.515$	$1.622$