State Snell’s law.

The refractive indices of glass, diamond and water are $1.5, 2.0$ and $1.33$ respectively. In which of these will the speed of light be maximum? Justify your answer with a suitable reason.

Give a suitable explanation for the given effect:

During sunset and sunrise, the sun is seen even when it is slightly below the horizon.

A beam of light consisting of red, green and blue colours is incident on a right-angled prism. The refractive index of the material of the prism for the above red, green and blue wavelengths are $1.39, 1.44$ and $1.47$, respectively. The prism will:

In figure, the optical fibre is $l= 2 \mathrm{m}$ long and has a diameter of $d=20 \mathrm{\mu m}$. If a ray of light is incident on one end of the fibre at angle ${\theta }_1=40°$, the number of reflection it makes before emerging from the other end is close to : (refractive index of fibre is $1.31$ and $\sin 40°=0.64$)

Yellow light of wavelength $600 \mathrm{nm}$ is incident on a boundary separating air and glass. Find the speed, wavelength and frequency of refracted light. The refractive index of glass for yellow light is $1.5$.