Question

Which colour of light has a higher critical angle? Red light or Green light.

Answer 1

Relation between critical angle and refractive index of medium is given by $\sin {\theta }_c=\frac{1}{n}$
where, ${\theta }_c$ is the critical angle and $n$ is the refractive index of medium.
Since refractive index of medium is lesser for red light as compared to green light i.e. $n_{Red}<n_{Green}$
$⟹\sin {\theta }_{c_{Red}}>\sin {\theta }_{c_{Green}}$
$⟹{\theta }_{c_{Red}}>{\theta }_{c_{Green}}$
Thus red light has higher critical angle than red light.