The focal length of a lens is $20 \ cm$ and its dispersive power is $0.08$. What is its longitudinal chromatic aberration in $cm$?

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:

Which of the following statements is incorrect?

What is dispersion of light?

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:

Explain the dispersion of white light.