The refractive index of glass is $1.5$ and that of water is $1.3$. If the speed of light in water is $2.25 \times 10^8 \, m/s$,what is the speed of light in glass?

The optical path of a particular ray of light that has travelled a distance of $3 \ cm$ in flint glass is the same as that of a ray travelling a distance of '$x$' $cm$ through another medium. The value of '$x$' is [refractive index of flint glass $= 1.6$, refractive index of another medium $= 1.25$]. (in $cm$)

When a ray of light of frequency $6 \times 10^{14} \ Hz$ travels from water of refractive index $4/3$ to glass of refractive index $8/5$,its

Clarify the meanings of optical density and mass density.

$A$ 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 $nm$)?

$A$ fish rising vertically at the rate of $3 \, m/s$ to the surface of water observes a bird above the water,diving vertically towards it at the rate of $9 \, m/s$. The refractive index of water is $4/3$. Calculate the actual velocity (velocity $w.r.t$ ground) of the bird in $m/s$.