Light of wavelength $7200 \ \mathring{A}$ in air. It has a wavelength in glass $(\mu = 1.5)$ equal to.......$\mathring{A}$

$A$ monochromatic beam of light is travelling from medium $A$ of refractive index $n_{1}$ to a medium $B$ of refractive index $n_{2}$. In the medium $A$,there are $x$ number of waves in a certain distance. In the medium $B$,there are $y$ number of waves in the same distance. Then,the refractive index of medium $A$ with respect to medium $B$ is

An infinitely long cylinder of radius $R$ is made of an unusual exotic material with refractive index $-1$ (See figure). The cylinder is placed between two planes whose normals are along the $y$-direction. The center of the cylinder $O$ lies along the $y$-axis. $A$ narrow laser beam is directed along the $y$-direction from the lower plate. The laser source is at a horizontal distance $x$ from the diameter in the $y$-direction. Find the range of $x$ such that light emitted from the lower plane does not reach the upper plane.

An observer can see through a pinhole,the top end of a thin rod of height $h$,placed as shown in the figure. The beaker's height is $3h$ and its radius is $h$. When the beaker is filled with a liquid up to a height $2h$,he can see the lower end of the rod. Then the refractive index of the liquid is

$A$ 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

An electromagnetic wave,whose wave normal makes an angle of $45^{\circ}$ with the vertical,travelling in air strikes a horizontal liquid surface. While travelling through the liquid it gets deviated through $15^{\circ}$. What is the speed of the electromagnetic wave in the liquid,if the speed of electromagnetic wave in air is $3 \times 10^8 \ m/s$? $(\sin 30^{\circ} = 0.5, \sin 45^{\circ} = \frac{1}{\sqrt{2}})$