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

Calculate the dispersive power for crown glass from the given data if $\mu_v = 1.5230$ and $\mu_r = 1.5145$.

$A$ medium is said to be dispersive,if

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.

Dispersive power depends on the following:

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 .........