$A$ glass slab of thickness $4 \ cm$ contains the same number of waves as $5 \ cm$ of water when both are traversed by the same monochromatic ray of light. The refractive index of water is $4/3$. What is the refractive index of glass?

$A$ printed page is kept pressed by a transparent cube of edge $t$. The refractive index of the cube varies as $\mu(z) = 1 + \frac{z}{t}$, where $z$ is the vertical distance from the bottom of the cube. If viewed from the top, then the printed letters appear to be shifted by an amount

$A$ fish rising vertically upward with a uniform velocity of $8\,ms^{-1}$ observes that a bird is diving vertically downward towards the fish with a velocity of $12\,ms^{-1}$. If the refractive index of water is $\frac{4}{3}$,then the actual velocity of the diving bird to pick the fish will be $.......\,ms^{-1}$.

Consider the situation shown in the figure. Water $\left( \mu_w = \frac{4}{3} \right)$ is filled in a beaker up to a height of $10 \, cm$. $A$ plane mirror is fixed at a height of $5 \, cm$ from the surface of the water. The distance of the image from the mirror after reflection of an object $O$ at the bottom of the beaker is......$cm$.

$A$ light wave is incident normally on a glass slab of refractive index $1.5$. If $4\%$ of light gets reflected and the amplitude of the electric field of the incident light is $30\, V/m$,then the amplitude of the electric field for the wave propagating in the glass medium will be.......$ V/m$

$A$ fish at a depth of $12 \, cm$ in water is viewed by an observer on the bank of a lake. To what height the image of the fish is raised? $....... \, cm$ (Refractive index of lake water $= 4/3$)