The time required for the light to pass through a glass slab (refractive index $= 1.5$) of thickness $4 \,mm$ is ($c = 3 \times 10^{8} \,m/s$, speed of light in free space).

$A$ narrow,paraxial beam of light is converging towards a point $I$ on a screen. $A$ plane parallel plate of glass of thickness $t$ and refractive index $\mu$ is introduced in the path of the beam. The convergence point is shifted by

The figure shows a ray of light entering and passing through a dense glass slab and emerging from the other side. If the angle of incidence $i=60^{\circ}$, slab thickness $b=0.04 \text{ m}$, and the refractive index of glass $\mu=\sqrt{3}$, the parallel shift $d$ between the emerging and entering rays in $\text{mm}$ is:

$A$ layer of oil $3\,cm$ thick is floating on a layer of coloured water $5\,cm$ thick. The refractive index of coloured water is $5/3$ and the apparent depth of the two liquids appears to be $36/7\,cm$. Find the refractive index of oil.

$A$ tiny air bubble in a glass slab $(\mu = 1.5)$ appears from one side to be $6 \, cm$ from the glass surface and from the other side,$4 \, cm$. The thickness of the glass slab is......$cm$

What is the time taken (in seconds) for light to cross a glass slab of thickness $4 \ mm$ and refractive index $\mu = 3$?