The frequency of a light wave in a material is $2 \times 10^{14} \ Hz$ and its wavelength is $5000 \ \mathring{A}$. The refractive index of the material will be:

Captain Jack Sparrow tries to observe a fish almost vertically below him in a magical sea of variable refractive index $\mu = y^2 + 1$,where $y$ is the depth below the water surface. Find the apparent depth of the fish below the water level as seen by Captain Jack Sparrow. The actual depth of the fish is $1 \ m$.

$A$ ray of light travelling in air has wavelength $\lambda$,frequency $n$,velocity $v$,and intensity $I$. If this ray enters into water,then these parameters are $\lambda'$,$n'$,$v'$,and $I'$ respectively. Which relation is correct from the following?

The distance travelled by light in glass (refractive index $= 1.5$) in a nanosecond will be.......$cm$.

When a light ray enters a medium with refractive index $\mu$,it is observed that the angle of refraction is half the angle of incidence. The angle of incidence is .........

$A$ light ray is incident on a glass slab at an angle of incidence of $60^o$. If the angle between the reflected ray and the refracted ray is $90^o$,what is the refractive index of the glass slab?