If the refractive indices of crown glass for red,yellow,and violet colours are respectively $\mu_r$,$\mu_y$,and $\mu_v$,then the dispersive power of this glass would be

Dispersion of light is due to

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?

Which of the following quantities related to a lens depend on the wavelength of the incident light?

Dispersive power depends upon

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: