H C Verma Solutions for Chapter: Dispersion and Spectra, Exercise 1: QUESTIONS FOR SHORT ANSWER

The equation $\omega =\frac{{\mu }_u-{\mu }_r}{\mu -1}$was derived for a prism having small refracting angle. Is it also valid for a prism of large refracting angle? Is it also valid for a glass slab or a glass sphere?

Can the dispersive power $\omega =\frac{{\mu }_v-{\mu }_r}{\mu -1}$ be negative? What is the sign of $\omega$ if a hollow prism is immersed into water?

If three identical prisms are combined, is it possible to pass a beam that emerges undeviated? undispersed?

"Monochromatic light should be used to produce pure spectrum". Comment on this statement.

Does focal length of a lens depend on the color of the light used? Does the focal length of a mirror depend on the color?

Suggest a method to produce a rainbow in your house.