$A$ cut diamond sparkles because of its

Light travels a distance '$x$' in time '$t_0$' in air and '$4x$' in time '$t_1$' in another denser medium. The critical angle for this medium is

The wavelengths of light in two liquids $x$ and $y$ are $3500 \, \mathring{A}$ and $7000 \, \mathring{A}$ respectively. The critical angle of $x$ with respect to $y$ is .......... $^o$.

$PQR$ is a right-angled prism with other angles as $60^o$ and $30^o$. The refractive index of the prism is $1.5$. $PQ$ has a thin layer of liquid. Light falls normally on the face $PR$. For total internal reflection at the face $PQ$,the maximum refractive index of the liquid is

Consider the ray diagram for the refraction given below. The maximum value of angle $\theta$ for which the light suffers total internal reflection at the vertical surface is:

$A$ ray of light travels from an optically denser medium to a rarer medium. The critical angle for the two media is $C$. The maximum possible deviation of the refracted light ray can be: