$A$,$B$ and $C$ are parallel-sided transparent media of refractive indices $n_{1}$,$n_{2}$ and $n_{3}$ respectively. They are arranged as shown in the figure. $A$ ray is incident at an angle $i$ on the surface of separation of $A$ and $B$. After refraction into medium $B$,the ray grazes the surface of separation of media $B$ and $C$. Then,$\sin i$ equals to

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

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.

Monochromatic light of frequency $5 \times 10^{14} \ Hz$ travelling in vacuum enters a medium of refractive index $1.5$. Its wavelength in the medium is ....... $\mathring{A}$.

$A$ ray of monochromatic light is incident on the plane surface of separation between two media $X$ and $Y$ with angle of incidence $i$ in medium $X$ and angle of refraction $r$ in medium $Y$. The given graph shows the relation between $\sin i$ and $\sin r$. If $V_X$ and $V_Y$ are the velocities of the ray in media $X$ and $Y$ respectively, then which of the following is true?

$A$ ray of light passes through four transparent media with refractive indices $n_{1}$,$n_{2}$,$n_{3}$,and $n_{4}$ as shown. The surfaces of all media are parallel. If the emergent ray $DE$ is parallel to the incident ray $AB$,then