The refractive index of a piece of transparent quartz is the greatest for

Consider the four different cases of dispersion of a light ray which has all the wavelengths from ${\lambda _1}$ to ${\lambda _2}$ (where ${\lambda _1} > {\lambda _2}$). The dotted line represents the light ray of wavelength ${\lambda _{avg}}$. Which ray diagram shows the maximum dispersive power?

If the refractive indices of crown glass for red,yellow,and violet colours are $1.5140, 1.5170$,and $1.5318$ respectively,and for flint glass these are $1.6434, 1.6499$,and $1.6852$ respectively,then the dispersive powers for crown and flint glass are respectively:

Let us list some of the factors,which could possibly influence the speed of wave propagation:
$(i)$ nature of the source.
$(ii)$ direction of propagation.
$(iii)$ motion of the source and/or observer.
$(iv)$ wavelength.
$(v)$ intensity of the wave.
On which of these factors,if any,does
$(a)$ the speed of light in vacuum,
$(b)$ the speed of light in a medium (say,glass or water),depend?

If the refractive indices of red,violet,and yellow lights are $1.42$,$1.62$,and $1.50$ respectively for a medium,its dispersive power will be:

The splitting of white light into several colours on passing through a glass prism is due to