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

Consider the four different cases of dispersion of a light ray which has all the wavelengths from ${\lambda _1}$ to ${\lambda _2}$ (where ${\lambda _1} > {\lambda _2}$). The dotted line represents the light ray of wavelength ${\lambda _{avg}}$. Which ray diagram shows the maximum dispersive power?

The dispersive power is maximum for the material

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:

What is a dispersive medium?

The focal lengths of a convex lens for red and blue light are $100 \text{ cm}$ and $96.8 \text{ cm}$ respectively. The dispersive power of the material of the lens is: