$A$ light of wavelength $600 \ nm$ in air enters a medium of refractive index $1.5$. Inside the medium :

There are certain materials developed in laboratories which have a negative refractive index. $A$ ray incident from air (medium $1$) into such a medium (medium $2$) shall follow a path given by

If light passes near a massive object,the gravitational interaction causes a bending of the ray. This can be thought of as happening due to a change in the effective refractive index of the medium given by $n = 1 + \frac{2GM}{rc^2}$,where $r$ is the distance of the point of consideration from the centre of the mass of the massive body,$G$ is the universal gravitational constant,$M$ is the mass of the body,and $c$ is the speed of light in vacuum. Considering a spherical object,find the deviation of the ray from the original path as it grazes the object.

The refractive index of glass is $1.6$ and the speed of light in glass will be . . . . . . . Speed of light in vacuum is $3 \times 10^{8} \,m \,s^{-1}$.

The refractive index of air with respect to vacuum is . . . . . . .

The wavelength of light diminishes $\mu$ times ($\mu = 1.33$ for water) in a medium. $A$ diver from inside water looks at an object whose natural colour is green. He sees the object as