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 dispersion for a medium of wavelength $\lambda$ is $D$. Then,the dispersion for the wavelength $2\lambda$ will be:

The dispersive power is maximum for the material

The refractive index of the material of the prism for violet colour is $1.69$ and that for red is $1.65$. If the refractive index for the mean colour is $1.66$,calculate the dispersive power of the material of the prism.

If the refractive indices of a prism for red,yellow,and violet colours are $1.61$,$1.63$,and $1.65$ respectively,then the dispersive power of the prism will be:

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: