The refractive index of a particular material is $1.67$ for blue light,$1.65$ for yellow light,and $1.63$ for red light. The dispersive power of the material is .........

Explain the refractive index for light of different colours.

Dispersion of light is due to

Dispersive power depends on the following:

The property of light that explains the formation of coloured images due to thick lenses is

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?