A light ray enters through a right angled prism at point $$P$$ with the angle of incidence $$30^{\circ}$$ as shown in figure. It travels through the prism parallel to its base $$B C$$ and emerges along the face $$A C$$. The refractive index of the prism is:

A small telescope has an objective of focal length $$140 \mathrm{~cm}$$ and an eye piece of focal length $$5.0 \mathrm{~cm}$$. The magnifying power of telescope for viewing a distant object is:

A lens is made up of 3 different transparent media as shown in figure. A point object O is placed on its axis beyond $$2f$$. How many real images will be obtained on the other side?

$$\epsilon_0$$ and $$\mu_0$$ are the electric permittivity and magnetic permeability of free space respectively. If the corresponding quantities of a medium are $$2 ~\epsilon_0$$ and $$1.5 ~\mu_0$$ respectively, the refractive index of the medium will nearly be :