Critical angle is that angle of incidence in the denser medium for which the angle of refraction in the rarer medium is......$^o$.

One of the necessary conditions for total internal reflection to take place is ($i =$ angle of incidence,$i_{c} =$ critical angle).

$A$ glass prism $(\mu = 1.5)$ is dipped in water $(_a\mu_w = 4/3)$ as shown in the figure. $A$ light ray is incident normally on the surface $AB$. It reaches the surface $BC$ after being totally internally reflected at the surface $AC$,if:

Rays from a point source of light situated at height $h$ below the liquid surface having refractive index $\mu$,form a circular patch of light of radius $r$ on the surface. The area of the patch is

$A$ fish inside water sees the outside world through a circular horizon. If the refractive index of water is $4/3$ and the fish is $12 \, cm$ below the water surface,then the radius of this circle is $= ..... cm$.

$A$ ray of light travelling in a transparent medium of refractive index $n$ falls on a surface separating the medium from air at an angle of incidence of $45^{\circ}$. For which of the following values of $n$ can the ray undergo total internal reflection?