In total internal reflection,when the angle of incidence is equal to the critical angle for the pair of media in contact,what will be the angle of refraction in degrees?

Total internal reflection of a ray of light is possible when the ($i_c$ = critical angle,$i$ = angle of incidence)

$A$ ray of light is incident at an angle $i$ from a denser to a rarer medium. The reflected and the refracted rays are mutually perpendicular. The angle of reflection is $r$ and the angle of refraction is $r'$. Then the critical angle $C$ will be:

Various optical processes are involved in the formation of a rainbow. Which of the following provides the correct order in time in which these processes occur?

The refractive index of glass is $1.5$ and that of water is $1.33$. The critical angle for a ray of light going from glass to water 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 .......... $^o$.