In refraction,light waves are bent on passing from one medium to a second medium because,in the second medium,

Light takes $8$ min $20$ sec to reach the Earth from the Sun. If the whole atmosphere were filled with water,how much time would the light take to reach the Earth? (Given refractive index of water,$_a\mu_w = 4/3$)

$A$ glass slab consists of thin uniform layers of progressively decreasing refractive indices $(RI)$ such that the $RI$ of any layer is $\mu - m \Delta \mu$. Here, $\mu$ and $\Delta \mu$ denote the $RI$ of the $0^{\text{th}}$ layer and the difference in $RI$ between any two consecutive layers, respectively. The integer $m = 0, 1, 2, 3, \ldots$ denotes the number of the successive layers. $A$ ray of light from the $0^{\text{th}}$ layer enters the $1^{\text{st}}$ layer at an angle of incidence of $30^{\circ}$. After undergoing the $m^{\text{th}}$ refraction, the ray emerges parallel to the interface. If $\mu = 1.5$ and $\Delta \mu = 0.015$, the value of $m$ is:

Which of the following graphs shows the appropriate variation of refractive index $\mu$ with wavelength $\lambda$?

The absolute refractive indices of glass and water are $\frac{3}{2}$ and $\frac{4}{3}$,respectively. The ratio of the velocity of light in glass to that in water will be:

If the wavelength of light in air is $4200\, \mathring A$,what will be the wavelength of light in water $(\mu = 4/3)$ in $\mathring A$?