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

$A$ light ray is incident on a spherical glass surface at an angle $\alpha$ and is refracted at an angle $\beta$. What is the angle of deviation between the emergent ray and the incident ray?

$A$ monochromatic light of frequency $5 \times 10^{14} \ Hz$ travelling through air is incident on a medium of refractive index $2$. What will be the wavelength of the refracted light (in $nm$)?

Give the meaning of $n_{12}$.

$A$ thin oil layer floats on water. $A$ ray of light making an angle of incidence of $40^o$ shines on the oil layer. The angle of refraction of the light ray in water is......$^o$ $({\mu _{oil}} = 1.45, {\mu _{water}} = 1.33)$

Light travels through a glass plate of thickness $t$ and having refractive index $n$. If $c$ is the velocity of light in vacuum,the time taken by the light to travel this thickness of glass is